JP2001277198A - Image display device, microstructure manufacturing method, and microstructure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a microstructure formed by joining together two or more joining components using a joining technique which ensures a wide selectivity for joint members, possibility of low- temperature joining, unlikelihood to generate distortion of the components due to joining, easiness in gap control between joint members, no emission of out-gas from the join and a high bonding strength, and to establish a microstructure of high quality using this joining technique. SOLUTION: A process to expose to halogenous gas is applied prior to the joining process to the joining surfaces of joining components to form a microstructure, and then the joining surfaces of the joining components are overlapped one over the other followed by heating and pressurizing so that a join is established which ensures a wide selectivity for joint members, possibility of low-temperature joining, unlikelihood to generate distortion of the components due to joining, easiness in gap control between joint members, no emission of out-gas from the join and a high bonding strength, and using this joining technique, it is possible to establish a microstructure of high quality.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for manufacturing a microstructure having a joining step of joining two or more components.

[0002]

2. Description of the Related Art In recent years, miniaturization of video projectors such as data projectors and video projectors has been further advanced, and video display devices have also become very small. For this reason, optical elements on the order of microns or sub-microns and video display devices equipped with the same have been developed. Similarly, in an optical communication device, an optical operation device, an optical recording device such as a hologram memory, an optical printer, etc., a microstructure (microstructure of micron order or submicron order) is used as a device of a system requiring high resolution and high speed response. The development of an optical device equipped with a) has been earnestly advanced.

[0003] Regardless of the aforementioned microstructure of the optical system, a technique of forming a microstructure by joining two or more components in any microstructure is very generally used. It is a technique that is often used as a joining technique used for forming a microstructure, and is used for joining of the same material, and after joining the joining faces of the mirror surfaces on which the hydroxyl groups are formed, pressurizing and temporarily joining,
Oxygen is released from the bonding surface by heating at high temperature, and strong bonding is achieved. Direct bonding, where the bonding surface of silicon and glass are overlapped, heated to 300 ° C or more, and a negative voltage of about 500 V is applied to the glass side. By this, alkali ions in the glass move to the negative electrode side, anodic bonding where bonding is achieved by electrostatic attraction by the space charge layer formed at the interface with silicon, the bonding surface of dissimilar metal parts are opposed, and heating is performed. In this case, eutectic bonding in which the eutectic portion of the bonding portion is formed to perform the bonding, and adhesive bonding in which the components are bonded via an adhesive can be given.

[0004]

However, the conventional joining techniques for forming a microstructure have the following problems.

[0005] Direct bonding has the advantage that very strong bonding can be obtained and that the same members are bonded, so that there is little occurrence of distortion due to heating. On the other hand, in order to perform bonding, it is necessary to use silicon at about 1100 ° C. 45 with silicon dioxide
Since a high temperature environment of around 0 ° C. and around 600 ° C. is required for compound semiconductors, a direct bonding technique is used when a member that is altered or melted at 400 ° C. or higher, such as aluminum, is used in the parts to be bonded. Have the problem of not being able to do so. Therefore, when a CMOS circuit having an aluminum wiring is included in the bonding component, direct bonding cannot be used.

[0006] The anodic bonding is very advanced technology, is easy to use, has high environmental resistance, and has the advantage of being able to perform strong bonding in a relatively low temperature environment of about 300 ° C. It is limited, the distortion due to heating is apt to occur due to the difference in the coefficient of linear thermal expansion of the joining members, sodium and the like are deposited on the surface of the glass, so it can be used almost only in the final step, and the gap between the joining members is large. Since the current flows, there is a problem that the CMOS circuit in the joint component is adversely affected, and its application is limited.

[0007] Eutectic bonding can be performed at a relatively low temperature lower than the melting point of each metal, and although alloy bonding has a strong bonding strength, the material that can be bonded is made of a dissimilar metal capable of forming a eutectic. There is a problem that it is limited to the combination and cannot be used for joining the same materials.

[0008] Adhesive bonding for joining two parts with an organic adhesive, a silicon adhesive, a low-melting glass or the like interposed therebetween can be easily performed in a low-temperature environment. Has the advantage of being able to avoid the problems of joining technology that requires high temperatures, but has a weaker joining strength than the other joining methods described above, and has the advantage that the adhesive can generate gas when heated during joining. When quality control is difficult such as generation of voids and adhesive bonding inside the vacuum sealed part or vacuum sealed cavity, the gas released from the adhesive during the lifetime will cause It is a cause that the degree of vacuum is deteriorated, dirt is easily generated, and it is very difficult to maintain a constant gap between members because a binder is interposed between the joining members. It has a problem.

[0009] The joining method of the microstructure should be a technique capable of joining at a low temperature in order to suppress the above-mentioned influence on members inside the component and to suppress occurrence of distortion of the component due to heating. In addition, it is required that environmental resistance is good, that gap management between joining members is easy, that no outgas is generated from the joining portion during processing or during the lifetime, etc., and that these conditions are satisfied. Above, it is also necessary to have strong bonding strength. Further, it is more convenient if there is a degree of freedom in selecting a joining member. As described above, the conventional joining techniques have respective advantages and disadvantages, and there is a problem that it is difficult to satisfy all of the conditions listed here.

Therefore, in the present invention, there is a high degree of freedom in the selectivity of the joining members, low-temperature joining is possible, distortion of components due to the joining process is unlikely to occur, and gap management between the joining members is easy. It is an object of the present invention to provide a joining technique that does not generate outgas from the joining portion and has a strong joining strength, and to provide a high-quality microstructure manufactured using the joining technique.

[0011]

In order to solve the above problems, according to the present invention, a halogen-based material is bonded to a bonding surface of a bonding part which forms a microstructure by bonding. In this method, a process of exposing in a gas atmosphere is performed, and thereafter, the joining surfaces of the joining components are overlapped with each other, and the components are joined by applying pressure while heating. By using the same method, it becomes possible to join parts even in a very low temperature environment, as compared with the case of joining by conventional direct joining or eutectic joining. Further, in the case of joining using this method, it may be possible to join materials that could not be joined by conventional direct joining or eutectic joining. In this joining, the halogen atoms mixed in the form of a halide into the joining surface by the pre-joining treatment are heated at the time of joining to move to the joining surface on the mating side, so that both members are joined between the joining surfaces. It is thought that progress will be made by promoting exchanges.

As described above, since parts can be joined in a low-temperature environment without using an adhesive for joining, problems such as generation of distortion and deterioration of members due to high-temperature heating at the time of joining, and problems of adhesive It is possible to solve various problems, such as the influence of gas released from the adhesive during processing or lifetime, and difficulties in managing the gap between the joined parts, which occur when using the method. In addition, a microstructure manufactured using this joining technique has high quality that has solved the above-mentioned problems.

In the present invention, the treatment with the halogen-based gas is performed by performing a corona discharge under an atmospheric pressure environment using a mixed gas of fluorocarbon and water as a reaction gas. Gas is sent to another room where the joint parts are placed. In this case, corona discharge is used only for generating the halogen-based gas, and there is no need to expose the directly joined components under corona discharge. Absent. In addition, according to this method, it is not necessary to increase the size of the chamber in which corona discharge occurs, and it is not necessary to prepare an apparatus for vacuum suction.
The apparatus for processing with the halogen-based gas is downsized,
It is possible to reduce the cost, and it is possible to realize a low manufacturing cost. In addition, this makes it possible to reduce the cost of the microstructure manufactured using the same manufacturing method.

In the present invention, the above-described bonding technique is applied to an image display device having microactuators arranged two-dimensionally on a substrate and operating in a direction perpendicular to the substrate, and having a micro-optical component above each microactuator. The above-described joining technology is used for joining the microactuator portion and the micro optical component of the image display device. As a result, since no binder is interposed between the microactuator and the micro optical component, the distance between the two members after joining can be reduced to zero, and the joining surface of both members before joining can be made flat. By controlling the degree, it is possible to uniformly manage the height of the optical component group after bonding. In addition, as described above, since bonding can be performed at a lower temperature than in the related art, it is possible to provide an image display device in which the members are not deteriorated and distortion due to heating is small.

The gas used for the treatment with the halogen-based gas contains a component (hydrogen fluoride) which is corrosive to silicon dioxide, and protects the silicon dioxide portion in the optical component from the corrosiveness. In order to perform the bonding, the bonding pretreatment with the halogen-based gas may be performed only on the microactuator side to perform the bonding. this is,
Even when only one of the bonding surfaces is subjected to the treatment with the halogen-based gas to perform the bonding, the bonding can be realized because there is no problem in strength. In this case, since the optical component side does not need to be exposed to corrosive gas, it is possible to perform joining using a treatment with a halogen-based gas without affecting the quality of the optical component made of silicon dioxide. Become. Therefore, a high-quality image display device can be provided by using this manufacturing method.

Further, in order to protect silicon dioxide in the optical component from corrosive components contained in the gas used for the treatment with the halogen-based gas, the surface of the silicon dioxide of the optical component is removed by a later sacrificial layer etching. A protective film is formed using the same member as the sacrificial layer to be formed, the optical component is subjected to the pre-joining process, then joined to a microactuator, and finally the protective film is peeled off during the sacrificial layer etching step. In the method of exposing the silicon dioxide surface of the optical component by, it is possible to protect the optical element from the corrosiveness of the halogen-based gas, using the same method,
It is possible to provide a high quality image display device.

In the present invention, silicon dioxide is used on both surfaces as a member of the bonding surface of the bonding by the above-mentioned bonding method, and while the conventional direct bonding takes about 450 ° C., the bonding method of the present invention is used. In this case, a sufficient bonding strength can be obtained at around 180 ° C. Silicon dioxide is easy to form a laminated film and its thickness by chemical vapor deposition, and it is relatively easy to process deep grooves with a high aspect ratio by dry etching. Despite being a high material, the problem is that the bonding temperature is too high for direct bonding. For anodic bonding, the mating member must be silicon. However, there is a problem that alkali ions need to be added, and there is a problem that warpage easily occurs after bonding, and there is a problem in using silicon dioxide as a member of a bonding surface. This makes it possible to use a material having high workability as the bonding surface.

Further, in the present invention, members such as gold, silver, copper, and tin may be used as members on the respective joining surfaces of the joining parts. Is possible.

As described above, by using the joining method of exposing the joining parts to a halogen-based gas atmosphere before joining, the selectivity of the members used for the joining surface can be increased.

By using the microstructure manufacturing technology described above, there is a high degree of freedom in selecting members for the bonding surface, low-temperature bonding is possible, distortion of parts due to bonding is small, and a gap between bonding portions is reduced. It is possible to provide a component joining technique that is easy to manage, generates little outgas from the joining portion, and has strong joining strength. In addition, by manufacturing using the same technology, a high-quality microstructure that has solved the above problems can be provided.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail while showing a manufacturing process of a video display device which is being developed by the present applicant.

FIG. 1 shows an outline of an image display device (evanescent light switching device) which modulates light using an evanescent wave (evanescent light) which is being developed by the present applicant. The video display device 50 is a device in which a plurality of optical switching elements (optical switching mechanisms) 10 are two-dimensionally arranged on a substrate 20. Each of the optical switching elements 10 is an optical element 3 capable of modulating light by approaching and separating from a light guide plate (light guide) 1 capable of totally reflecting and transmitting the introduced light 2 by itself.
And an actuator 6 for driving the optical element section 3. Then, by manufacturing an optical element (micro-optical element) and an actuator (micro-actuator) on the order of microns, an optical element is formed on the semiconductor substrate 20 on which a drive circuit for driving the actuator and a digital storage circuit (storage unit) are built. The layer of the element 3 and the layer of the actuator 6 can be laminated, and a chip-sized device integrated as one image display device can be provided.

The image display device 50 of this embodiment using evanescent light will be described in more detail.
Explaining based on the individual optical switching elements 10,
The optical switching element 10a illustrated on the left side of FIG. 1 is in an on state, and the optical switching element 10b illustrated on the right side is in an off state. The optical element 3 has a surface (contact surface or extraction surface) 3a that is in close contact with the surface (total reflection surface) 1a of the light guide plate 1 (light guide) that functions as a waveguide, and this surface 3a is the total reflection surface 1a. A V-shaped reflecting prism (microprism) 4 that extracts an evanescent wave that leaks out when it comes into close contact and reflects the evanescent wave inside in a direction substantially perpendicular to the light guide plate 1, and supports the V-shaped prism 4. And a V-shaped groove support structure 5.

The actuator 6 is capable of electrostatically driving the optical element 3. An upper electrode 7 to which the support structure 5 of the optical element 3 is mechanically connected, and a lower electrode 8 opposed to the upper electrode 7. And And the lower electrode 8,
The anchor plate 9 of the upper electrode 7 is disposed on the uppermost surface 20a of the semiconductor substrate 20. The upper electrode 7 is supported by a support 11 extending upward from the anchor plate 9,
A space is formed between the lower electrode 8 and the upper electrode 7. Therefore, for example, when the upper electrode 7 is grounded via the plate 9 and a potential or electric charge is applied to the lower electrode 8 from the drive unit 21 (hereinafter referred to as a high potential), the upper electrode 7 moves downward and interlocks with this. As a result, the optical element section 3 is separated from the light guide plate 1 (second position). On the other hand, the upper electrode 7 partially has a function as an elastic member, and the potential or charge applied to the lower electrode 8 from the drive unit 21 is removed or released (hereinafter, low potential).
Then, the upper electrode 7 is separated from the lower electrode 8, and the optical element unit 3 is brought into close contact with the light guide plate 1 by the elasticity of the upper electrode 7 (first position).

As shown in FIG. 1, the light guide plate 1 is supplied with the illumination light 2 from the light source at an angle at which the illumination light 2 is totally reflected by the total reflection surface 1a. Light is repeatedly totally reflected on the side 1a facing the light switching portion 3 and on the upper surface (emission surface), and the inside of the light guide plate 1 is filled with light rays. Therefore, in this state, the illumination light 2 is macroscopically confined inside the light guide plate 1 and propagates therein without any loss. On the other hand, microscopically, in the vicinity of the surface 1a of the light guide plate 1 which is totally reflected, the illumination light 2 leaks from the light guide plate 1 only for a very short distance of about the wavelength of light, and changes its course. The phenomenon of returning to the inside of the light guide plate 1 again occurs. The light leaked from the surface 1a in this manner is generally called an evanescent wave. This evanescent wave can be extracted by bringing another optical member close to the total reflection surface 1a at a distance of about the wavelength of light or less.
The optical switching element 10 of the present embodiment is designed to modulate light transmitted through the light guide plate 1 at high speed, that is, to switch (on / off) using this phenomenon.

Therefore, in the optical switching element 10a, since the optical element 3 is at the first position in contact with the total reflection surface 1a of the light guide plate 1, an evanescent wave can be extracted by the surface 3a of the optical element 3. For this reason, the light 2 extracted by the microprism 4 of the optical element 3 is changed in angle and becomes the output light 2a. On the other hand, the optical switching element 10
In b, voltages having different polarities are applied to the upper and lower electrodes 7 and 8 by the drive unit 21, and these electrodes 7 and 8 are applied.
The optical element 3 is moved to the second position apart from the light guide plate 1 by the electrostatic force acting during the period. Therefore, the evanescent wave is not extracted by the optical element 3, and the light 2 does not exit from the inside of the light guide plate 1.

An optical switching element using an evanescent wave functions as a device that can switch light by itself, but as shown in FIG.
It is configured so that it can be arranged in a three-dimensional direction, or even three-dimensionally. In particular, by arranging two-dimensionally in a matrix or array, it is possible to provide a video display device or an image display unit 55 capable of displaying a two-dimensional image similarly to liquid crystal or DMD. In the image display device 50 using evanescent light, the moving distance of the optical element 3 is on the order of submicron, so that it can be used as a light modulator having a response speed one digit or more faster than that of liquid crystal. Alternatively, a direct-view image display device can be provided. Further, the optical switching element 10 using evanescent light can turn on and off light by almost 100% with a movement on the order of submicron,
An image with very high contrast can be expressed. For this reason, it is easy to increase the temporal resolution, and a high-contrast image display device can be provided.

Further, as described above, the video display device 50 having a configuration in which the actuators 6 and the optical elements 3 arranged in an array on the semiconductor integrated substrate 20 in which the drive circuit and the like are built is provided in one chip. It is possible to That is, the image display unit 55 can be provided by assembling the image display device 50, which is a micromachine or an integrated device, in which the microstructure such as the actuator 6 and the optical element 3 is constructed on the semiconductor substrate 20, and the light guide 1. By incorporating the above, it is possible to provide a projector which can display a high-contrast image with a high operation speed and a high resolution.

The switching device using the evanescent light is not limited to the one shown in FIG. 1. For example, in addition to the upper electrode 7 and the lower electrode 8, an intermediate electrode that moves between them is provided. An image display device having an actuator 6 configured to drive the optical element 3 is also possible. The video display device using the evanescent light has a merit that the configuration of the actuator 6 is complicated but can be driven at a low voltage. Furthermore, instead of electrostatic actuators using electrodes,
It is also possible to configure an actuator using a piezo element, and several actuators have been considered. Therefore, in the following description, the description will be made based on an actuator of an electrostatic drive type with upper and lower electrodes for simplicity, but the configuration of the actuator is not limited to this.

Hereinafter, the present invention will be described with reference to the method of manufacturing the optical switching device 50 using the evanescent light shown in FIG.

First, as shown in FIGS.
Then, a layer to be the actuator 6 is manufactured on the “0”. As shown in FIG. 2, an electrode layer (aluminum film) 31 is deposited on the upper surface 20a of the substrate 20 on which the CMOS is formed. Next, the electrode layer 31 is patterned 41 to form the lower electrode 8 and the anchor portion 9 having a structure also serving as a spring and an upper electrode.

As shown in FIG. 3, a sacrificial layer 32 is deposited on the electrode 31. The sacrificial layer 32 can be deposited at about 250 ° C. using amorphous silicon, and does not damage the CMOS circuit formed on the underlying semiconductor substrate 20. A dimple 42 serving as a stopper is dug in the sacrificial layer 32, and a portion to be a post is patterned 43.

As shown in FIG. 4, on the sacrificial layer 32, a second electrode layer (aluminum film) 33 serving as a second structural layer for forming the structure 7 serving as both a spring and an upper electrode is deposited. I do. Further, the electrode layer 33 is patterned to form the upper electrode 7 and the post 11. At this stage, a structure as the actuator section 6 is formed on the semiconductor substrate 20.

Further, as shown in FIG. 5, a silicon dioxide film 34 is laminated on the second electrode layer 33 by a chemical vapor deposition method, and is patterned to form a micro optical element 3 on the actuator section 6. Is formed. The temperature required for stacking the silicon film 34 is about 250 ° C., and does not damage the CMOS circuit formed on the underlying semiconductor substrate 20. Up to this stage, a fine structure layer (actuator array layer) 25 that functions as the actuator 6 is formed.

Next, a glass substrate 70 is prepared separately from the semiconductor substrate 20, and the actuator 6 is placed on the glass substrate 70.
A method for forming an optical element array layer 26 in which the optical elements 3 which can be moved by the operation of the actuator by joining them later will be described. 6 to 9
9 schematically shows a process of manufacturing the optical element array layer 26. First, as shown in FIG. 6, a silicon layer 71 is formed on a glass substrate 70 polished on both sides by using a chemical vapor deposition method or sputtering. Further, a silicon dioxide layer 35 is stacked on the upper surface of the silicon layer 71 by a chemical vapor deposition method.

Next, a photoresist 72 is coated on the silicon dioxide layer 35, soft-baked, exposed using a gray level mask having a pattern having a different transmittance on the mask, and developed. A V-shaped resist 72 is formed as shown in FIG. When the reactive ion etching is performed from above the shape of the resist 72 in FIG. 6, as shown in FIG. 7, the V-shape of the resist is vertically expanded by the selection ratio between the resist and silicon dioxide. V-shaped shapes can be created. In the present embodiment, it is created so that the final V-shaped slope angle φ is 30 °.

Subsequently, as shown in FIG. 8, a reflective film 46 is deposited on the V-groove of the silicon dioxide layer 35 formed in FIG. Further, a silicon dioxide layer 36 is laminated on the reflective film 46, and after lamination, the upper surface of the silicon dioxide layer 36 is polished to create a flat surface following the lower surface of the glass substrate 70. By this polishing step, after the actuator array layer 25 and the optical element array layer 26 are bonded and the glass substrate 70 is peeled off, the heights of the upper surfaces of the microprisms 4 arranged in an array can be made uniform.

Thereafter, a photoresist is applied on the polished silicon dioxide layer 36, pattern exposure is performed, and development is performed. Then, reactive ion etching is performed using the resist as a mask material, as shown in FIG. The device is divided into dice by digging a groove 73 penetrating the three layers of the silicon layer 36, the reflection film 46, and the silicon dioxide layer 35, and the optical element array layer 26 is formed. Each of the divided optical elements is connected to the actuator array layer 25 by a later bonding process.
Silicon dioxide layer 35
Will function as the microprism 4 and the silicon dioxide layer 36 will function as the support structure 5 of the microprism 4, and each of the divided optical elements will function as one pixel of the video display device 50.

The actuator array layer 2 is formed by using a bonding technique of performing a processing using a fluorine-based gas for a bonding pre-processing to be described later.
5 and the optical element array layer 26 are connected to the joint portion 44 formed on the actuator and the support structure 5 of the microprism.
Then, the sacrifice layer 32 made of amorphous silicon is removed by performing dry etching of the silicon sacrifice layer using xenon difluoride gas or the like as the respective polished surfaces. This makes it possible to completely remove the sacrificial layer without causing the problem of adsorption even in a narrow gap between the electrodes or the like, and to reliably form the driving space 12 between the electrodes. Therefore, a reliable actuator 6 can be realized. At the same time as the etching of the sacrificial layer, the silicon layer 71 between the silicon dioxide layer 35 and the glass substrate 70 is etched, and the glass substrate 70 can be separated from the optical element array layer 26. FIG. 10 shows a state in which the optical switching element has been manufactured after bonding, sacrificial layer etching, and glass substrate peeling.

The method described above makes it possible to form the optical element 3 with the microprisms 4 driven by individually separated actuators 6.
The device manufactured by the manufacturing method of the present embodiment is a video display device 50 in which the actuator 6 and the optical element 3 that are microstructure layers are vertically stacked on the semiconductor substrate 20. The image display unit 55 based on the technology of the optical switching element 10 using the evanescent light described with reference to FIG. 1 can be provided by combining with the light guide plate 1.

Hereinafter, the actuator array layer 25 and the optical element array layer 2 in the above-described embodiment will be described.
A detailed description will be given of a joining method for performing a pre-joining process using a fluorine-based gas, which was used to join the substrates 6.

FIG. 11 shows an outline of a pre-bonding process using a fluorine-based gas to be bonded in this embodiment.
As raw material gas, carbon tetrafluoride is fed from the conduit 81 at a flow rate of 30 ccm, and steam at a flow rate of 1 ccm is fed from the conduit 82. The source gas is a fluorine-based gas generation chamber 8
3 where the carbon tetrafluoride and steam are mixed. Make the gas generation chamber a temperature of 100 ° C and atmospheric pressure,
Using the mixed gas as a reaction gas, a peak voltage of 7 kV and a frequency of 25 kHz are applied between the comb electrodes 91 in the gas generation chamber 83.
To generate a corona discharge. As a result of this corona discharge, a gas containing hydrogen fluoride (HF), carbonyl difluoride (COF2), fluorine (F2) and the like is generated. The gas generated here is sent to a bonding surface treatment chamber 85 through a conduit 84.

The microstructure 92 to be bonded is set in the bonding surface processing chamber 85 in advance, and the processing chamber 8
The surface of the bonding surface is treated with a fluorine-based gas by exposing it to the generated gas sent from the conduit 84 inside the inside 5. It is considered that fluorine atoms are mixed in the form of fluoride near the bonding surface of the microstructure to be bonded by the same process. The treated gas passes through conduit 86 and is exhausted through an exclusion device.

In the pre-bonding treatment using a fluorine-based gas, corona discharge is used only to generate a gas for the treatment, and it is not necessary to use a large-scale mechanism.
It is possible to easily reduce the size and cost of an apparatus for performing treatment using a fluorine-based gas.

The two parts are joined by aligning and superimposing the joint part treated with the fluorine-based gas with the other joint part, and heating while applying pressure. The bonding process after this pre-bonding treatment with fluorine-based gas is the same as conventional eutectic bonding and direct bonding, but it is possible to perform bonding in a low-temperature environment compared to conventional bonding without the same pre-treatment. Become. For example, when trying to join gold (Au) and tin (Sn) by eutectic bonding, the eutectic point is 273 ° C., but tin is pretreated with a fluorine-based gas and bonded with gold. In this case, a eutectic portion is formed at about 180 ° C., and bonding having the same bonding strength as eutectic bonding can be performed. The bonding principle is that the heating during the bonding process causes the fluorine atoms mixed into the bonding surface in the pre-bonding process with the fluorine-based gas to move to the mating surface of the mating member, thereby forming a member between the mating surfaces. It is considered that the movement is promoted, an alloy layer is formed near the joint surface, and the joint proceeds.

The above-mentioned treatment with the fluorine-based gas can sufficiently exhibit its effect regardless of whether the treatment is performed on only one side or both of the parts to be joined.

As a pre-treatment of the joining step as described above, a joining technique requiring high-temperature heating is performed by using a technique in which a joint component is treated with a fluorine-based gas and then joined in a low-temperature heating environment. Thus, problems such as generation of distortion and deterioration of members, which are apt to occur due to the above, can be avoided without using adhesive bonding having problems such as management of bonding strength and gap between parts and outgassing.

The gas used for the pre-joining treatment contains hydrogen fluoride (HF) and is corrosive to silicon dioxide. Therefore, when the member of the bonding surface is made of silicon dioxide, the process of mixing fluorine atoms simultaneously proceeds while etching the silicon dioxide. Since the amount of hydrogen fluoride in the fluorine-based gas is very small, the etching amount of silicon dioxide is less than 1000 angstroms, and there is no particular problem regarding the bonding surface of silicon dioxide and the influence on the silicon oxide film of the substrate 20. However, when the optical component whose surface accuracy is required is made of silicon dioxide, as in the above-described image display device 50, there is a case where the execution of the treatment with the fluorine-based gas adversely affects the quality of the device. . In this case, as described above, even if the pre-bonding process using the fluorine-based gas is performed only on one side of the bonded component, there is a sufficient effect on the bonding. Therefore, in the case of the video display device 50, the component on the actuator array 25 side is used. If only the same bonding pretreatment is performed and bonding is performed, it is possible to perform component bonding according to the present invention without having any effect on the optical element 3 in which quality is likely to be degraded due to corrosion.

However, in the above-described method for manufacturing an image display device, the upper surface of the microprism 4 which needs the most protection from deterioration is removed during the sacrificial layer etching step until the sacrificial layer etching step after the component bonding step. Is protected by a silicon layer 71 made of the same material as the other sacrifice layer, and by etching the sacrifice layer of silicon after bonding, the upper surface of the protected prism 4 is exposed. Even if the processing with the gas is performed on the components on the optical element array 26 side, this does not cause a serious problem. As described above, as a method of protecting the member from the gas during the treatment with the fluorine-based gas before joining the components, it is also effective to protect the protected portion with the same material as the sacrificial layer and simultaneously remove the same portion when etching the sacrificial layer. It is a way.

In this embodiment, silicon dioxide is used on both surfaces as a member for the bonding surface. in this case,
By applying a pressure of 2 kilograms per square centimeter in an environment of 180 ° C. for 30 minutes, practically sufficient bonding strength can be obtained. Silicon dioxide has good workability and is often used as a material for microstructures.However, with conventional bonding technology, it was difficult to use as a bonding surface. Depending on the joining technique, it can be used as a material for the joining surface.

In this embodiment, an example in which silicon dioxide is bonded to each other as a material of the bonding surface has been described. However, gold (Au), silver (Ag), copper (Cu), tin (Sn) Similarly, when a metal such as) is used, bonding having sufficient strength can be performed at a low temperature. For example, gold (A
In the case where a combination of u) and copper (Cu) is used as a joining member, by applying a pressure of 3 kilograms per square centimeter for 60 seconds in a 250 ° C. environment after the treatment with the fluorine-based gas, joining with sufficient strength can be achieved. Achieved. As described above, by using the joining technique of the present invention, a great degree of freedom can be obtained in selecting the joining members.

[0052]

As described above, according to the present invention, 2
When one or more microstructures are joined to form one microstructure, the microstructures to be joined are exposed to a halogen-based gas as a pre-joining process, and the joining is performed by applying pressure while heating. Has been implemented. This method enables joining in a low-temperature process that does not use an adhesive. Problems such as distortion and deterioration of components due to joining at a high temperature, and the effect of gas emitted from the adhesive due to the use of an adhesive. And, it is possible to eliminate the problem of weak adhesive strength and difficulties in managing the gap between the joined parts, and a fine structure manufactured using this manufacturing method has a high quality that clears the above-mentioned problems. It will be. The pre-joining process using a halogen-based gas described above is performed by using a mixed gas of fluorocarbon and water as a reaction gas and performing corona discharge treatment under an atmospheric pressure environment. It is possible to easily process with a halogen-based gas before joining without the need for large-scale equipment, and it is possible to reduce the price of microstructures manufactured using this technology Becomes Further, the bonding technique is applied to an image display device having microactuators arranged two-dimensionally on a substrate and operating in a direction perpendicular to the substrate, and having micro optical components on top of each microactuator. By using the above-mentioned joining technology to join the micro-actuator part and the micro-optical part, the height of the micro-optical part group of the device can be controlled uniformly, and furthermore, image display without distortion and deterioration of members It becomes possible to provide devices. further,
Halogen-based gas treatment is performed only on components without optical members, or the protection target is protected by the same member as the sacrifice layer that is removed in the sacrifice layer etching step, and exposed after the sacrifice layer etching. The optical component can be protected from the corrosiveness of the system gas, and the deterioration of the optical component can be avoided, so that a high-quality image display device can be provided. Also, by using the bonding technology of the present invention, silicon dioxide, gold, silver,
Since metals such as copper and tin can be used, the degree of freedom in selecting a joining member can be further expanded.

As described above, by using the joining technique of the present invention, the members of the joining surface can be freely selected, the joining can be performed at a low temperature, the distortion of the parts due to the joining can be reduced, and the distance between the joining portions can be reduced. It is easy to manage the gap, and it is possible to provide parts with strong joint strength without generating outgas from the joint, and by using this technology, it is possible to provide high quality which has solved the above problems Can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing an outline of a video display device using evanescent light.

FIG. 2 is a diagram illustrating a manufacturing process of the optical switching element illustrated in FIG. 1, illustrating a state in which a first electrode layer is formed on a semiconductor substrate.

FIG. 3 is a diagram illustrating a manufacturing process of the optical switching element illustrated in FIG. 1, illustrating a state in which a first sacrificial layer is formed on a first electrode layer.

FIG. 4 is a view illustrating a process of manufacturing an actuator on a semiconductor substrate, and is a view illustrating a state in which a second electrode layer (spring layer) is formed on a first sacrificial layer.

FIG. 5 is a diagram showing a state in which a joint with a micro optical element is formed on a semiconductor substrate.

FIG. 6 is a view showing a process of manufacturing a microprism on a glass substrate, and showing a state in which a silicon layer and a silicon dioxide layer are formed on the glass substrate.

FIG. 7 is a view showing a step after the process shown in FIG. 6, showing a state in which a V-groove is formed in the microprism layer.

8 is a view showing a step after the process shown in FIG. 7, showing a state in which a reflecting film and a support structure for the micro prism are formed on the micro prism layer.

FIG. 9 is a view showing a step after the process shown in FIG. 8, showing a state in which the microprism is separated for each pixel.

FIG. 10 is a diagram showing a state in which an optical switching element is manufactured by bonding a semiconductor substrate and a glass substrate, removing a sacrifice layer, and peeling the glass substrate.

FIG. 11 is a diagram showing an outline of a process using a halogen-based gas before bonding according to the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 light guide plate (light guide) 2 incident light 3 optical element (movable piece) 4 microprism 5 support structure layer 6 actuator 7 upper electrode and spring structure 8 lower electrode 9 anchor 10 optical switching element 11 post (post) 20 semiconductor substrate 25 Actuator array layer 26 Optical element array layer 32 Sacrificial layer 44 Junction with optical element 50 Optical switching device 55 Image display device 70 Glass substrate 83 Fluorine-based gas generation chamber 84 Pre-joining processing chamber 91 Comb-tooth upper electrode 92 Fineness of joining target Structure

Claims (13)

[Claims] In a method of manufacturing a microstructure formed by joining two or more joining parts, a step of joining the two parts to one is a step of joining both or one of the joining surfaces with a halogen. A method for producing a microstructure, comprising: a step of superposing two surfaces to be joined together after heating in a system gas atmosphere, and heating while pressurizing to join the joined surfaces. 2. A microstructure manufactured by using the manufacturing method according to claim 1. 3. The method according to claim 1, wherein a corona discharge is caused under atmospheric pressure using fluorocarbon and water as reaction gases, and a gas generated by the discharge is sent to another chamber in which the joint parts are set in advance. A method for producing a microstructure, comprising: performing a pre-joining treatment with the halogen-based gas by exposing the joining component to a generated gas. 4. A microstructure manufactured using the manufacturing method according to claim 3. 5. The image display device according to claim 4, wherein the microstructure has microactuators arranged two-dimensionally on the substrate and operating in a direction perpendicular to the substrate, and a microoptical component on each microactuator. An image display device, wherein a manufacturing method is used in which the microactuator unit and the micro optical component are joined after pre-joining treatment with the halogen-based gas. 6. An image according to claim 5, further comprising a manufacturing method of performing a bonding pretreatment with the halogen-based gas only on the component having the microactuator and then bonding the component with the micro optical component. Display device. 7. The micro optical component according to claim 5, wherein after forming a protective layer on the surface of the micro optical component using the same member as the sacrificial layer of the microstructure, pre-joining treatment with the halogen-based gas is performed. Joined to a part having an actuator,
An image display device having a manufacturing method of exposing a surface of a micro optical component by finally performing sacrificial layer etching. 8. The method for manufacturing a microstructure according to claim 1, wherein the joining surfaces of the two parts to be joined are formed of silicon dioxide, respectively, and the joining is performed. 9. A microstructure manufactured using the manufacturing method according to claim 8. 10. An image display device according to claim 5, wherein the image display device is manufactured using the manufacturing method according to claim 8. 11. A microstructure according to claim 1, wherein the joining surfaces of the two parts to be joined are formed of a combination of metallic materials such as gold, silver, copper, tin and the like, and are joined. Production method. 12. A microstructure manufactured using the manufacturing method according to claim 11. 13. An image display device according to claim 5, wherein the image display device is manufactured by using the manufacturing method according to claim 11.