JP3972587B2 - Manufacturing method of fine structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of manufacturing a fine structure suitable for manufacturing a micromachine such as an optical switching device having micron or submicron micro optical elements.
[0002]
[Prior art]
As an image display device capable of controlling on / off of light as a light valve of an image display device such as a projector, a device using liquid crystal is known. However, the image display device using this liquid crystal has poor high-speed response characteristics and operates only at a response speed of about several milliseconds. Therefore, an apparatus that displays a high-resolution image that requires a high-speed response, an optical recording apparatus such as optical communication, optical calculation, hologram memory, and an optical printer are realized by a switching device using liquid crystal. Is difficult.
[0003]
Accordingly, there is a need for a switching device or an image display device capable of high-speed operation that can be used for the above-described applications, and eagerly develops a switching device having a micro structure on the micron order or a smaller submicron order. It is being advanced.
[0004]
[Problems to be solved by the invention]
One of them is an application filed by the applicant of the present application. The evanescent light is extracted by bringing the extraction surface of the switching unit into contact with the total reflection surface of the light guide unit capable of transmitting the light by total reflection. Alternatively, it is an optical switching device that can modulate and control light at a high speed by a minute movement smaller than that.
[0005]
FIG. 1 shows an outline of a projector 180 as an example of an image display device using an image display device (optical switching device) that performs switching by evanescent light. The projector 180 includes a white light source 181, a rotating color filter 182 that separates the light from the white light source 181 into three primary colors and enters the light guide plate (light guide) 1 of the image display unit (light switching unit) 55; An image display unit 55 that modulates and emits light of each color and a projection lens 186 that projects the emitted light 185 are provided. Then, the modulated light 185 for each color is projected onto the screen 189 and mixed with time to output a multi-tone multicolor image. The projector 180 further includes a control circuit 184 that controls the image display unit 55 and the rotation color filter 182 to display a color image. The image display unit 55 includes a light guide 1 and an image display device (light switching device) 50 described in detail below. Data φ for displaying a color image from the control circuit 184 is an image display device. 50.
[0006]
As described above, the projector 180 shown in FIG. 1 includes the lens 185 that projects the light emitted from the light guide 1 together with the light source 181 that supplies light for projection to the light guide 1 that transmits light while totally reflecting light. And an image display device 50 that modulates the projection light supplied to the light guide 1. The image display device 50 controls evanescent light leaking from the light guide 1. An image is displayed.
[0007]
FIG. 2 shows an outline of an image display device (evanescent light switching device) 50 that modulates light using evanescent waves (evanescent light). The image display device 50 is a switching device in which a plurality of optical switching elements (optical switching mechanisms) 10 are two-dimensionally arranged, and each optical switching element 10 can transmit the introduced light 2 by totally reflecting it. An optical element (switching unit) 3 capable of modulating light by approaching and moving away from a light guide plate (light guide) 1 and an actuator 6 that drives the optical element 3 are provided. Then, the layer of the optical element 3 and the layer of the actuator 6 are laminated on the semiconductor substrate 20 on which the drive circuit and the digital storage circuit (storage unit) for driving the actuator 6 are built, and as one image display device 50. It is integrated.
[0008]
The image display device 50 of this example using evanescent light will be described in more detail with reference to FIG. Describing based on the individual optical switching elements 10, the optical switching element 10a shown on the left side of FIG. 2 is in the on state, and the optical switching element 10b shown on the right side is in the 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 that functions as a waveguide, and the surface 3a is in close contact with the total reflection surface 1a. A V-shaped prism (microprism 4) for extracting leaked evanescent waves, a reflective film 46 for reflecting the bottom surface of the prism 4 in a direction substantially perpendicular to the light guide plate 1, and a V-shaped prism 4 and a support structure 5 that supports 4.
[0009]
The actuator 6 is of a type that electrostatically drives the optical element 3, and for this purpose, an upper electrode (first electrode) 7 that is mechanically connected to the support structure 5 of the optical element 3 and moves together with the optical element 3, A lower electrode (second electrode) 8 fixed to the semiconductor substrate 20 at a position facing the upper electrode 7 is provided. Further, the upper electrode 7 is supported by a column 11 extending upward from the anchor plate 9.
[0010]
As shown in FIG. 2, the illumination light 2 is supplied from the light source to the light guide plate 1 at an angle at which it is totally reflected by the total reflection surface 1a, and all the interfaces inside it, that is, the optical element section (light switching section). ) The light is repeatedly totally reflected on the side 1a facing 3 and the upper surface (outgoing surface), and the light guide plate 1 is filled with light. Accordingly, in this state, the illumination light 2 is macroscopically confined inside the light guide plate 1 and propagates through the light without loss. On the other hand, microscopically, in the vicinity of the totally reflecting surface 1a of the light guide plate 1, the illumination light 2 is once leaked from the light guide plate 1 by a very small distance of the wavelength of light, and the course is changed. The phenomenon of returning to the inside of the light guide plate 1 again occurs. The light leaking from the surface 1a is generally called an evanescent wave. This evanescent wave can be taken out 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 this example is designed for the purpose of modulating, that is, switching (on / off) the light transmitted through the light guide plate 1 at high speed using this phenomenon.
[0011]
For example, in the optical switching element 10a of FIG. 2, since the optical element 3 is in 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 by the reflection film 46 to become outgoing light 2a. The emitted light 2a is used as projection light 185 of the projector 180 shown in FIG. On the other hand, in the optical switching element 10 b, the optical element 3 is moved to the second position away from the light guide plate 1 by the electrostatic force acting between the electrodes 7 and 8. Therefore, no evanescent wave is extracted by the optical element 3, and the light 2 does not exit from the inside of the light guide plate 1.
[0012]
An optical switching element using an evanescent wave functions as a device capable of switching light alone, but as shown in FIG. 2, a configuration in which these can be arranged side by side in a one-dimensional or two-dimensional direction, or even in a three-dimensional manner. It has become. In particular, by arranging two-dimensionally in a matrix or array, a video device or image display unit 55 that can display a planar image in the same manner as a liquid crystal or DMD can be provided. In the image display device 50 using evanescent light, the moving distance of the optical element 3 serving as a switching unit is on the order of submicrons, so that it can be used as a light modulation device having a response speed one digit or more faster than that of liquid crystal. Thus, it is possible to provide a projector 180 or a direct-view image display device that can operate at high speed. Furthermore, the optical switching element 10 using evanescent light can turn on and off light almost 100% with submicron order motion, and can express a very high contrast image. For this reason, it is easy to increase the temporal resolution, and a high-contrast image display apparatus can be provided.
[0013]
Furthermore, in this optical switching device 50, the image display device 50 having a configuration in which the actuators 6 and the optical elements 3 arranged in an array are stacked on the semiconductor integrated substrate 20 in which a drive circuit or the like is built is provided in one chip. It is possible. That is, the image display unit 55 can be supplied by assembling the image display device 50 and the light guide 1 which are a micromachine or an integrated device in which a microstructure such as the actuator 6 and the optical element 3 is constructed on the semiconductor substrate 20. By incorporating the projector, it is possible to provide a projector capable of displaying a high-contrast image with high operation speed and high resolution.
[0014]
Further, the actuator 6 is not limited to the one having a pair of upper and lower electrodes in FIG. 2, and is provided with an intermediate electrode moving between these in addition to the upper electrode 7 and the lower electrode 8. Instead of the electrostatic actuator used, it is possible to configure the actuator using a mechanism capable of supplying a driving force by other electrical signals such as a piezo element, and several actuators are considered. Therefore, in the following description, for the sake of simplicity, description will be made based on an electrostatic drive type actuator having upper and lower electrodes, but the configuration of the actuator is not limited to this.
[0015]
Such a switching device can manufacture a hybrid microstructure including each layer, for example, an actuator layer having a high driving performance and an optical element layer having a high optical performance, by a photolithography technique or the like.
[0016]
However, the manufacturing process of each layer is different, so each layer is manufactured with different equipment or at different timing, and then the layers (actuator layer and optical element layer) are combined by techniques such as mold transfer and substrate bonding. Manufacturing of fine structures such as optical switching devices has been studied. Separating each manufacturing process has the advantage of facilitating optimization of the manufacturing process and facilitating quality control, but on the other hand, when combining parts (structural layers) manufactured on two different substrates There is also a problem that the positions need to be matched with high accuracy. For example, considering the case where the actuator layer and the optical element layer are separately manufactured and overlapped, these structural layers are very small parts of about 10 μm to about 10 μm, but these are one-to-one. If it is not laminated corresponding to the above, it does not act as a switching element or it is difficult to obtain a desired operation (action). That is, in the optical switching device described above, the optical element turns on and off the light at a desired position following the movement of the actuator. Therefore, if the alignment (combination) of these is poor, the contrast is lowered and the screen brightness is lowered. It becomes a factor of image quality degradation.
[0017]
As described above, in the alignment (alignment) of each part, a minute shift affects the quality of the device (fine structure). On the other hand, in the fine structure, since each size is very small, one of the merits is that a plurality of devices can be manufactured on one wafer (substrate). Therefore, there is no variation over the entire wafer. Uniform positional accuracy is required. Furthermore, a layer between the structural layers formed when the separately manufactured structural layers are bonded together is also one of the structures of a microstructure, for example, a switching device. Therefore, it is necessary to manage the thickness of the layer to which the structural layer is attached in order to manufacture a fine structure with high accuracy. As described above, in the manufacturing method in which the respective structural layers are combined, the film thickness of the structure sandwiched between them and the alignment thereof are important factors.
[0018]
Further, if there is a problem in alignment or film thickness control, expensive layers produced by those layers and photolithography technology up to the semiconductor circuit and the structural layer are wasted, so that the economic loss is large.
[0019]
Therefore, an object of the present invention is to provide a manufacturing method suitable for manufacturing a microstructure by combining layers having a microstructure. Furthermore, it is possible to form a layer with a desired uniform thickness as a whole, and to easily and accurately align the upper and lower layers to be bonded at the same time, and to produce a highly reliable, high-quality microstructure with good yield. It aims to provide a method.
[0020]
[Means for Solving the Problems]
For this reason, in the present invention, in a manufacturing method in which a structural layer formed on an individual substrate faces and a new structural layer is sandwiched therebetween, a resin including a gap material between the facing substrates By sandwiching the layers, the newly formed structural layer can be managed to the same thickness over the entire substrate, and the gap agent is interposed between the upper and lower substrates, making it easy to adjust the alignment to match their relative positions. In addition, it is possible to do with high accuracy.
[0021]
That is, according to the present invention, the first substrate having the first structural layer and the second substrate having the second structural layer are combined so that the first and second structural layers face each other to form a chip. A method of manufacturing a microstructure having a step of forming a third structure layer that becomes a part of the microstructure to be formed, wherein the step of forming the third structure layer includes the first and second structure layers. The first resin layer to be the third structural layer is applied so as to be sandwiched between the first and second structural layers, and the gap material is sandwiched between the first and second substrates. Applying the included second resin layer; adjusting the alignment of the first and second substrates so that the relative positions of the first and second structural layers are in a desired state; And a step of curing the resin layer.
[0022]
Since the gap material is a granular material having a substantially uniform size, the gap between the first and second substrates can be controlled by these. Furthermore, the gap material is included in the second resin layer and applied to form a desired structure between the first and second substrates facing each other, that is, as a fine structure within the first and second substrates. It is possible to place a gap material in a place where the chip is not formed, and the thickness of the third structural layer can be managed without affecting the third structural layer. Further, since the gap material is a granular solid, the first and second substrates can be moved relatively easily with a desired gap opened by overlapping the first and second substrates sandwiching them. It is possible to adjust the alignment easily, and the alignment can be performed with high accuracy. Therefore, according to the manufacturing method of the present invention, the substrate in which the structure layer is built can be accurately stacked, and the third structure layer with high accuracy can be formed between them. Can be manufactured with good yield. Since the manufacturing method of the present invention can prevent a decrease in device yield due to poor alignment and poor film thickness management, the microstructure can be mass-produced economically.
[0023]
In addition, the first or second structure layer is not limited to being a part of the fine structure, and may be a transfer type formed on the first or second substrate. According to the manufacturing method, the third structural layer or the fine structure in which the third structural layer and the first or second structural layer are combined is manufactured.
[0024]
In order to efficiently manage the gap between the first and second substrates, the second resin layer including the gap material may be applied so as to be sandwiched between at least three locations of the first and second substrates. desirable. Further, in the applying step, it is desirable to apply while avoiding alignment marks for aligning the first and second structural layers in a desired position. For this reason, it is desirable to determine the application amount and the application position in consideration of the fluidity (viscosity) of the first and second resins to be applied and the gap material.
[0025]
In the step of forming the third structural layer, subsequent to or simultaneously with the coating step, the first and second structures are sandwiched between the first and second substrates outside the first and second structural layers. It is desirable to provide a step of applying the third resin layer so as to surround the layer. Accordingly, the first resin layer can be sealed from the outside by the third resin layer in a state where the first resin layer serving as the third structural layer is sandwiched between the first and second substrates. Therefore, after the third resin layer is formed in a reduced pressure environment or an inert gas environment, it is possible to move to a place where it is exposed to the outside air, making the manufacturing process flexible, and handling the workpiece in the middle of manufacturing. Improves.
[0026]
It is desirable to provide a temporary fixing step of curing the second resin layer before the step of curing the first resin layer. Thereby, after adjusting alignment, the 2nd resin layer can be hardened in a short time, and the 1st resin layer can be hardened in the state where positioning and thickness were determined. Further, even when the curing method of the first resin layer is different from that of the second resin layer, it is easy to cope with it. For example, the second resin layer can be UV cured (photocured) in the temporary fixing process, and then the first resin layer can be thermally cured in the process of curing the first resin layer. In this manufacturing method, even when the first and / or second structural layer includes a metal layer such as aluminum, the first resin layer is cured, and the microstructure having the third structural layer is provided. The body can be easily manufactured.
[0027]
The gap material included in the second resin layer may be a polygonal granular material such as a filler. However, the gap material is managed with high accuracy, and the first and second substrates are relatively moved. In terms of facilitating, a spherical member having a predetermined tolerance diameter, such as that used in liquid crystal panels, is desirable.
[0028]
Although it is possible to use a gap material having a size matching the distance between the first and second substrates, there is not always a gap material having a size suitable for managing a desired gap. Therefore, conversely, it is desirable to form a structure in accordance with the size of the gap material in the region of the first and / or second substrate on which the second resin layer is applied. Thereby, the thickness of the third structural layer is not restricted by the size of the gap material, and the entire gap can be managed to a constant thickness even if the thickness is smaller or larger.
[0029]
Furthermore, it is desirable to provide a step of heating the second resin layer including the gap material before adjusting the alignment. Thereby, since the fluidity of the second resin layer is improved, the substrates can be moved relatively easily during alignment. By similarly heating the first resin layer, the fluidity is increased, so that the resistance force when moving the substrates is reduced, and alignment is facilitated.
[0030]
In the coating step, a plurality of chip areas in which a plurality of fine structures are aggregated are formed by the first and / or second substrate by the formation of the third structural layer, and a dicing process is performed in units of chips. It is desirable to apply the second resin layer to the regions of the first and second substrates that are cut off by dicing. During the dicing process, the second resin layer is automatically removed and discarded. Therefore, the finally obtained microfabricated chip does not include the second resin layer, and it is not necessary to newly provide a process for removing the second resin layer, and the handling is easy.
[0031]
In addition, the first and second substrates may be a part of the microstructure manufactured by the manufacturing method of the present invention, and even if the microstructure does not include the substrate, It can be manufactured by the manufacturing method of the invention. A substrate unnecessary as a microstructure, for example, the second substrate is formed by forming the second structural layer on the second substrate with the release layer interposed therebetween, and then forming the third structural layer. By providing the step of peeling the substrate, a microstructure that does not include the second substrate can be manufactured and provided.
[0032]
Further, at least a part of the second substrate may be a part of a microstructure to be chipped. In other words, the second substrate itself can be processed into a second structure layer. In the present invention, the second structure layer is not limited to a resin material, but a fine structure including an inorganic material structure layer. It can also be applied as a production method for obtaining a body.
[0033]
Furthermore, as described above, it is also possible to use a mold transfer substrate with an appropriate shape processed as the second substrate. In this case, after forming the third structural layer, this mold transfer is performed. A step of peeling the second substrate which is the substrate is provided.
[0034]
When a micromachine such as the above-described optical switching device is manufactured by the method for manufacturing a fine structure of the present invention, the first structural layer only needs to have a portion that functions as an actuator. For example, an electrostatic actuator can be employed. A micromachine can be manufactured by forming an element driven by an actuator with the second and third structural layers. Furthermore, an optical switching device can be manufactured by using the element as an optical element. And according to the manufacturing method of the microstructure of the present invention, the micromachine and the switching device as shown in FIG. 2 can be manufactured with low cost and high accuracy.
[0035]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail while showing a process of manufacturing the optical switching device 50 shown in FIG. 2 by the manufacturing method of the present invention. FIG. 3 is a flowchart showing a series of flows for manufacturing the optical switching device (image device) 50 by forming the optical switching elements 10 in an array on the semiconductor substrate 20. In addition, FIGS. 4 to 9 schematically show the respective processes. In the process of this example, the actuator 6 is formed on the semiconductor substrate 20, a part of the optical element 3 is formed on another substrate, and these are combined. In other words, this is a method for manufacturing a microstructure by manufacturing or bonding a structure layer of the microstructure on separate substrates.
[0036]
First, in step 111 of FIG. 3, as shown in FIG. 4, an actuator layer 60 serving as a first structural layer is formed on the upper surface of a semiconductor substrate (first substrate) 20 on which a CMOS circuit is configured. The actuator 6 of this example is an electrostatic drive type, and the electrode 8 and the upper electrode 7 serving as a spring are made of aluminum. Then, the amorphous silicon is manufactured as a sacrificial layer 99 by a photolithography technique.
[0037]
Next, in step 112, as shown in FIG. 5, the prism layer 42 as the second structural layer is formed on the glass substrate 96 as the second substrate. This prism layer 42 becomes the microprism 4 of the optical element 3. In this process, an inorganic material silane (SiH) is formed on the surface of the glass substrate 96. _Four ) Is deposited by plasma CVD under the condition of about 580 ° C. to form a release layer 97 of amorphous silicon. Further, by a plasma CVD method, TEOS (tetraepoxide silane) is deposited as a plasma source under a low temperature condition of a substrate temperature of 300 ° C. to form a silicon oxide prism layer (second structural layer) 42. Then, the V-groove (V-shaped) prism layer 42 having an angle with a triangular cross section is processed by wet etching by photolithography. It is also possible to form a V-shaped shape by mold transfer or an etching technique using a gray mask. Further, an Al—Nd material is sputtered on the surface 42 a along the shape of the V-shaped prism layer 42 to form a V-shaped reflective film 46. In this way, the V-shaped prism layer 42 is formed on the glass substrate 96.
[0038]
Next, in step 113, as shown in FIG. 6 and FIG. 7, the glass substrate 96 as the second substrate is placed on the semiconductor substrate 20 as the first substrate, and the actuator layer 60 as the first structural layer. The support layer 41 to be the third structural layer is formed between the substrates 20 and 96 by being bonded so as to face the prism layer 42 which is the second structural layer. The support layer 41 becomes a resin support structure 5 that is a part of the optical element 3, and the prism layer 42 is supported by the actuator 6. In this example, first, as shown in FIG. 6, the surface of the reflective film 46 serving as the interface (connection surface) of the second structure layer and the surface of the actuator layer 60 serving as the interface of the first structure layer are coupled. Surface treatment with material. Thereafter, an appropriate amount of epoxy (EP) material, which is the first resin material 71 to be the support layer 41, is applied to the surface of the actuator layer 60 in a plurality of points. Further, it may be applied by spin coating so as to have a uniform film thickness. Further, in this example, as will be described in detail later, a second resin material 73 including a spherical gap material 72 is provided in a region 79 where the support layer 41 serving as the third structural layer such as the outer periphery of the substrate 20 is not formed. Apply.
[0039]
Next, as shown in FIG. 7, the prism layer 42 processed into a V shape on the second substrate 96 and the EP material applied on the actuator layer 60 on the first substrate 20. The glass substrate 96 and the semiconductor substrate 20 are combined so that 71 faces each other. At this time, as will be described in detail later with reference to FIG. 10 and thereafter, the second resin layer 73 is formed in the region 79 outside the region where the EP material 71 for forming the support layer 41 is applied. It is sandwiched between the second substrates 96. The second resin layer 73 includes a spherical gap material 72 having a predetermined tolerance and a particle diameter of about 2 to 3 μm. Therefore, since the second resin layer 73 including the gap material 72 is interposed between the first substrate 20 and the second substrate 96, the distance G between the substrates 20 and 96 can be maintained at a desired value. The film thickness or shape of the support layer 41 manufactured by the EP material 71 sandwiched therebetween can be made uniform.
[0040]
Further, since the gap material 72 exists between the first and second substrates 20 and 96 and the gap material 72 is granular and substantially contacts the substrates 20 and 96 at points, the first and second substrates 20 and 96 are It is relatively easy to move. Further, even if it is moved, the gap G between the substrates is defined by the gap material 72, so that the thickness does not change. Therefore, the horizontal relative positions of the upper and lower substrates 20 and 96 can be easily adjusted, and the substrates 20 and 96 are aligned at desired positions while looking at the alignment marks, and the actuator layers 6, the support layers 41, and the prism layers are aligned. It can laminate | stack so that 42 may be in a desired state.
[0041]
And in the state which maintained the desired position, it heat-processes on the conditions of 180-330 degreeC, and forms the support layer 41. FIG. As a result, the EP material 71 sandwiched between the actuator layer 60 and the prism layer 42 is formed into a V-shaped support layer (third structure layer) 41, thereby joining (adhering) the prism layer 42 to the actuator layer 60. ).
[0042]
At this stage, as shown in FIG. 7, a structure (optical switching device) as a switching element for driving the optical element 3 by the actuator 6 can be constructed on the semiconductor substrate 20. Further, in this example, the second substrate 96 supporting the prism layer 42 is removed. Therefore, a UV laser is applied to the amorphous silicon release layer 97 formed between the prism layer 42 and the glass substrate 96, for example, 308 nm, 230 mJ / cm. ² Irradiate under the following conditions. As a result, the glass substrate 96 can be separated (peeled) while leaving the configuration on the semiconductor substrate 20 side from the silicon oxide prism layer 42 on the semiconductor substrate 20.
[0043]
Next, in step 114 shown in FIG. 3, the actuator layer 60, the support layer 41, and the prism layer 42 stacked on the silicon substrate 20 shown in FIG. I do. Therefore, the surface 42a of the prism layer 42 is subjected to a coupling process, and although not shown here, a photoresist material is spin-coated, pre-baked, a pixel pattern is formed, and further post-baked. In accordance with this developed patterning, the prism layer 42 of silicon oxide is made C _Four F ₈ + Ar + H ₂ Then, the reflective film 46 of Al-Nd is made Cl. ₂ And BCl _Three Then, the EP material support layer 41 is changed to O. ₂ RIE processing. This O ₂ In the RIE process, the photoresist on which image patterning is formed can be removed.
[0044]
As a result, as shown in FIG. 9, the optical element 3 composed of the second structural layer 42 and the third structural layer 41 is pixel-separated, and a gap S is formed vertically across the second and third structural layers. Is done. Further, through this gap S, XeF ₂ Thus, a part of the sacrificial layer 99 of silicon is removed. As a result, the optical switching devices 55 arranged in an array can be obtained.
[0045]
In step 115, a plurality of optical switching elements 10 are set as a set and diced into units of optical switching devices 50 as shown in FIGS. At this stage, the adhesive 73 containing the gap material 72 applied in FIG. 6 is also discarded.
[0046]
Then, in step 116 of FIG. 3, the remaining silicon sacrificial layer 99 of each chip (optical switching device) 50 is XeF. ₂ Remove with. As a result, a chip-shaped optical switching device (microstructure) 50 is completed.
[0047]
Further, the process for forming the third structural layer in step 113 in FIG. 3 will be described in detail with reference to FIGS. 10 to 17 so that each layer is in a desired relative position.
[0048]
First, in step 120 of FIG. 10, the first and second resin layers are applied. As shown in FIG. 11, the material used as the resin layers 71 and 73 is prepared, respectively. First, as the first resin material 71 used for the third structural layer (support layer) 41, in this example, an epoxy-based epoxy-based (EP material) that can be UV-cured and thermally cured is used. Moreover, as the 2nd resin layer 73, the same EP material is used, About 0.5 to 5 weight% gap material 72 is added and mixed with this. Examples of the gap material 72 to be added include Micropearl SP-203 manufactured by Sekisui Chemical Co., Ltd., which was developed as a gap material for liquid crystal panels. For example, the average particle size is 3.00 μm ± 0.05 μm. You can use the thing of the grade. Gap materials such as micropearl have high compressive strength and heat resistance. Accordingly, when the gap member 72 is sandwiched between two substrates, it can play a role of regulating the thickness by its size. In addition to this, since the particles are in contact with the substrate at points, they can roll while supporting the substrates 20 and 96, or can support these substrates 20 and 96 with a small friction coefficient.
[0049]
Next, as shown in FIG. 12 schematically showing the first substrate 20 as viewed from above, the two types of resin materials 71 and 73 thus prepared are applied. First, the surface shape 42a of the processed substrate 96 shown in FIG. 5 is measured, and the amount (volume) of the first resin 71 necessary for forming the support layer 41 shown in FIG. 7 is obtained. And the 1st resin material 71 is apply | coated to the area | region in which the actuator layer 60 of the board | substrate 20 was formed in multiple numbers. In this example, about 0.1 to 50 mg of the first resin material 71 is measured with a syringe and applied. Further, the second resin material 73 including the gap material 72 is applied to the region 79 where the actuator layer 60 is not formed. At this time, avoiding the alignment mark M attached to the substrate 20 and applying a plurality of points at an appropriate location so that the mark M does not spread even when pressed. In order to maintain an appropriate gap G over the entire surface of the substrate 20, it is desirable to apply a second resin material 73 containing a gap material to at least three places. Furthermore, the second resin material 73 including the gap material 72 is also applied so as to be about 16 μg while being measured with a syringe, so that the second resin material 73 is out of a desired range when pressurized. Prevent spreading.
[0050]
The region 79 to which the second resin material 73 is applied is a portion that is not formed into a chip and that is cut off when dicing is performed later (step 105) and is not sandwiched between the actuator layer 60 and the prism layer 42. The position between the first and second substrates 20 and 96.
[0051]
Further, in this example, a third resin (which may be the same as the first or second resin) 75 of an appropriate material is applied along the outer peripheral portion 20 c of the first substrate 20. This resin material 75 is for sealing (sealing) between the first and second substrates, and spreads along the outer peripheral portion 20c when pressurized, so that the outer peripheral portion 20c can be sealed. To do. After the substrates 20 and 96 are bonded together by the third resin layer 75, the inner resin materials 71 and 73 are isolated from the atmosphere.
[0052]
Next, returning to FIG. 10, in step 121, the two substrates 20 and 96 are combined to face each other. First, as shown in FIG. 13, the first substrate 20 coated with the resin materials 71, 73 and 75 and the second substrate 96 on which the prism layer 42 is formed are set on the jig 100. The jig 100 is provided with holders 102 and 103 for supporting the substrates on the upper and lower sides, respectively, and the structural layers 60 and 42 respectively formed on the substrates 20 and 96 by the holders 102 and 103 are provided. Hold up and down to face each other. Further, in the figure and the subsequent figures, the shape of the actuator 60 formed on the first substrate 20 is omitted.
[0053]
A heater 105 is disposed in a holder 103 that holds a substrate on one side to which resin is applied, in this example, the lower substrate 20. The heater 105 is controlled by a temperature adjustment unit 106. The temperature can be adjusted. In the manufacturing method of this example, before the second substrate 96 is bonded, the substrate 105 is heated to about 45 ° C. by the heater 105 and maintained in that state for 5 minutes. Thereby, the temperature of resin apply | coated to the board | substrate 20 can be raised, clay can be lowered | hung, and those fluidity | liquidity can be improved.
[0054]
Next, as shown in FIG. 14, the first substrate 20 and the second substrate 96 including the jig 100 are placed in the chamber 101, and the inside of the chamber 101 is decompressed to about 0.2 Torr or less. Maintain for 5 minutes. Thereby, gas can be extracted from the applied resin, in particular, the first resin 71, and it is possible to prevent a situation in which bubbles remain during molding or a problem occurs because gas is generated after manufacturing. Furthermore, in this example, the resin is also heated by heating the substrate 20, so that the gas can be easily removed.
[0055]
Then, as shown in FIG. 15, the second substrate 96 on which the V-shaped prism layer 42 is formed is overlaid on the first substrate 20, and the first substrate 20 and the second substrate 96 are bonded together. Do. At this time, the inside of the chamber is depressurized to 0.2 Torr or less, and there is no air that becomes an obstruction factor when the point-coated resin spreads, and the formation of a thin film is facilitated. In addition, it is possible to suppress the generation of a bond that becomes a problem when performing photolithography in the pixel separation step, and to form a smooth surface. This state is maintained for about 5 minutes, and the first and second resin materials 71 and 73 between the substrates are made to conform.
[0056]
Further, as shown in FIG. 16, the bonded first and second substrates 20 and 96, i.e., the work 59, are pressurized in the chamber 101 from below by a pressurizer 107 at about 0.3 MP. This state is maintained for about 10 minutes, and the first resin material 71 is spread as a whole to form a support layer 41 made of resin. As will be described later, at this time, the gaps (vertical direction in this figure) G sandwiched between the two substrates by the respective gap materials 72 of the second resin 73 applied to the region 79 of the substrate 20 are made uniform. Can keep. Therefore, the support layer (third structure layer) 41 managed to have a uniform thickness over the entire substrate can be formed.
[0057]
In addition, the third resin material 75 applied along the periphery 20 c of the substrate 20 forms a seal layer on the periphery 20 c of the first substrate 20 and the second substrate 96. Therefore, even if the work 59 is taken out from the chamber 101, the support layer 41, which is the third structural layer formed by the first resin layer 71, is not exposed to the outside air.
[0058]
Next, as shown in step 122 of FIG. 10, the alignment is adjusted. For this reason, the bonded first and second substrates 20 and 96 are taken out of the chamber 101 and set in an alignment apparatus (aligner) having a UV exposure function. This UV exposure apparatus is also used for mask alignment in a semiconductor process, and for example, a bond aligner BA6 manufactured by Carl Zose Japan Co., Ltd. can be used. The exposure apparatus includes a stage that can align the substrates, and can adjust the alignment of the two substrates stacked on the top and bottom in the order of 1 μm. The substrate can be temporarily secured.
[0059]
In the manufacturing method of this example, the bonded substrates 20 and 96 are set on the aligner, and the alignment mark M attached to the substrate 20 is adjusted according to the guide (reference). At this time, Each resin material is maintained in a fluid state. Further, as schematically shown in an enlarged view in FIG. 17, a spherical gap material 72 is included between the upper and lower substrates 20 and 96 in addition to the resin material 71 that becomes the support layer 41. A resin material (resin layer) 73 is sandwiched, and for example, the substrate 96 is supported by the gap material 72 with respect to the substrate 20. Since the gap material 72 is granular, the substrate 96 is almost supported at a point, and at this point, it is easy to move. Since the position (gap G) in the up / down (vertical) direction is always defined by the gap material 72, the upper and lower substrates 20 and 96 are generally moved even if the positions of the substrates 20 and 96 are relatively moved. The desired gap G can be maintained without moving evenly. Furthermore, the gap material 72 of this example is particularly spherical, and rolls like a bearing between the substrates 20 and 96 that are in contact with the gap material 72. Furthermore, the gap G does not change even if it moves easily. Therefore, the alignment (horizontal direction) of the substrates 20 and 96 can be smoothly adjusted while maintaining the state in which the thickness of the workpiece 59 (support layer 41) is controlled.
[0060]
Then, when the alignment is adjusted so as to be a desired relative position, in Step 123 of FIG. 10, the second resin layer is UV-exposed and cured, and the upper and lower substrates 20 and 96 are temporarily aligned. It is fastened. At this time, since the other resin material 71 is formed with the aluminum reflective film 46, the UV does not hit the resin material 71 and is not cured. However, the work (bonded substrates 20 and 96) 59 is fixed with sufficient accuracy by curing the second resin material 70.
[0061]
Next, in step 124 of FIG. 10, the work 59 shown in FIG. 16 is taken out from the alignment apparatus and put in an oven (not shown) and subjected to heat curing. In this example, heating is performed at 120 ° C. for 60 minutes to cure the resin support layer 41, and a V-shaped third structure layer 41 is formed between the actuator layer 60 and the prism layer 42. The As described above, in the work 59 of this example, the prism layer 42 that is the second structural layer includes the aluminum layer 46 that is the reflective layer, and thus the first resin that becomes the third structural layer. The layer cannot be UV cured. For this purpose, a thermosetting process is employed, but the process of moving from the chamber 101 to the oven by forming the third resin layer 75 when the first resin 71 is applied under reduced pressure in the chamber 101. Therefore, even if the work 59 is exposed to the outside air, the first resin layer 71 is not exposed to the outside air, and the second resin 73 is cured with UV and temporarily fixed, so that the position accuracy can be maintained even if the work 59 is moved to the oven. To prevent deterioration.
[0062]
At this stage, the support layer 41 to be the third structural layer is formed, and then, as described with reference to FIG. 3, the second substrate 96 is peeled, pixels are separated, and a chip is formed (diesing). When the sacrificial layer 99 is removed, the optical switching device 55 as shown in FIG. 2 can be manufactured.
[0063]
The microstructure of this example is an optical switching device in which the optical switching elements 10 are arranged in an array, and can be supplied as one chip. And since the size of each device is very small, one of the merits is that a plurality of devices (chips) can be manufactured on one wafer (substrate). As described above, the entire wafer can be uniformly controlled to a desired thickness through the gap material 72, and alignment can be ensured. For this reason, it is possible to manufacture a large number of chips with high accuracy in a single manufacturing process, which is a manufacturing method suitable for mass production of fine structures. In addition, since a highly reliable and high-quality fine structure can be obtained, misalignment and film thickness failure can be prevented, and the device yield can be greatly improved. Therefore, a fine structure can be provided at low cost without wasting the expensive substrate 20 manufactured up to the actuator layer by photolithography technology in addition to the semiconductor circuit.
[0064]
Furthermore, as schematically shown in FIGS. 18A to 18D, the present invention can be similarly applied to a manufacturing method of a fine structure using mold transfer. First, as shown in FIG. 18A, a transfer mold (transfer substrate) 81 in which a desired V-shaped (V groove) 82 is processed is prepared as a second substrate. As shown in FIG. 18B, on the side of the semiconductor substrate 20 on which the actuator layer 60 that is the first substrate is formed, an epoxy-based resin material that becomes the third structural layer 41 as in FIG. 71 is applied, and a resin material 73 containing a gap material 72 is applied around the substrate or the like. The substrates 20 and 81 are combined so as to face each other with the resin materials 71 and 73 sandwiched therebetween. Then, as shown in FIG. 18C, pressurizing with an appropriate force from above or below while accustoming the resin. At this time, in the manufacturing method of this example, the parallelism of the substrates 20 and 81 can be maintained as a whole by the particulate gap material 72, and the gap G between the substrates 81 and 20 can be maintained at a desired thickness. Furthermore, as described above, the alignment can be adjusted so that the relative position between the lower actuator layer 60 and the V groove of the transfer mold 81 is in a desired state.
[0065]
Then, when desired alignment and the like are completed, UV irradiation is performed, the resin materials 71 and 73 are cured, and the transfer die 81 is removed. As shown in FIG. 18D, the actuator is placed on the semiconductor substrate 20. A layer 60 and a V-shaped support layer 41 are formed thereon. Although not shown, a reflective film 46 such as aluminum is formed on the surface. Further, mold transfer (using a flat substrate), the same process as described above is repeated to form the prism layer 42 shown in FIG. Thus, the optical switching device 50 as shown in FIG. 2 can be obtained. Therefore, even in the manufacturing method using the mold transfer 81 shown in FIG. 18, by applying the present invention, the structural layer formed between the two substrates can be manufactured uniformly. The relative position of can be easily adjusted. For this reason, the optical switching device 50 with high accuracy and high reliability can be easily manufactured at low cost.
[0066]
In addition, the resin material mentioned above is an illustration and is not limited to them. For example, “World Lock No. XOC-03H2” manufactured by Kyoritsu Chemical Industry Co., Ltd., which is an ultraviolet curable epoxy adhesive, and “ThreeBond 2088F” manufactured by ThreeBond Co., Ltd., which is a bisphenol type epoxy resin. and so on. Resins based on modified alicyclic polyamines and polyamide amines are excellent in terms of less outgassing, but have a short pot life (about 1 day at room temperature) and are cumbersome to handle.
[0067]
Further, the resin containing the gap material is not limited to the above, but “Aron Ceramic D, N, W, D-4, D-5.N4” manufactured by Toa Gosei Co., Ltd. containing alumina oxide (ceramic). There is. This is excellent in that no outgassing occurs. There is also “HL4210J2” manufactured by Dexter Co., Ltd., an epoxy resin for LED. This is excellent in that it has a long pot life and does not cure until heated. Furthermore, there is “Dotite XA-974” manufactured by Fujikura Kasei Co., Ltd., which is an epoxy resin and contains a conductive filler (such as Ag). Thus, not only a spherical gap material but also a polygonal one can be applied to the present invention as long as it has a particle size within a suitable tolerance range.
[0068]
In the manufacturing method of this example, it is desirable to process the shape of the substrate 20 or 96 in accordance with the size of the gap material 72 shown in FIG. In particular, the region to which the second resin material 73 including the gap material 72 is applied does not affect the structural layer and can be processed arbitrarily. For example, as shown in FIG. 19, a step 96d is provided on the second substrate 96 side. By this step 96d, the third structure layer made of the resin material 71 can be uniformly manufactured even below the size (particle diameter) of the gap material 72 to be used. Even in this case, the gap material 72 can easily adjust the alignment as described above.
[0069]
In addition, the manufacturing method of the microstructure of this invention is not limited to the example applied to the optical switching device 50 using the evanescent light mentioned above. For example, FIG. 20 shows an optical switch device 256 which is a micromachine to which the method for manufacturing a microstructure according to the present invention can be applied. In the state shown in FIG. 20A, the optical switch device 256 of this example is retracted to an area where the light shield 254 does not hinder the transmission of the optical signal 257, and the optical signal 257 emitted from the emission-side optical fiber 251. Is received by the light receiving side optical fiber 252 through the space 258, and the optical signal 257 is transmitted. On the other hand, in FIG. 20B, the light shielding object 254 appears in the space 258, and the light signal 257 is not transmitted to the light receiving side optical fiber 252 by blocking the optical signal 257 by the light shielding object 254. Therefore, the micromachine of this example is an optical switch device 256 that can switch the transmitted optical signal 257 in the space 258 by using the light shield 254.
[0070]
The structure of the micromachine optical switch device 256 is such that a light shielding portion 254 serving as a third structural layer of the manufacturing method of the present invention is laminated on a piezo actuator 250 serving as a first structural layer. Is stacked on a silicon substrate (first substrate) 210 on which a circuit 211 for driving the circuit is built. The drive circuit 211 controls power supply to the piezo actuator 250 by the switch 212. Further, a post 202 formed by the first structural layer extends from the surface of the silicon substrate 210, and a piezo actuator 250 and an optical fiber fixing base 253 formed by the third structural layer are stacked. Yes.
[0071]
In the micromachine having such a structure, first, the piezo actuator 250 of the driving unit, which is the first fine structure, and the post 202 are manufactured on the substrate 210 by a photolithography process. Then, the light-shielding object 254 and the optical fiber fixing base 253 as the third structure layer are manufactured using the mold transfer substrate provided with the second structure layer as the second substrate. At the same time, an optical fiber fixing V-groove 255 for fixing the optical fiber by mold transfer is formed on the fixing base 253. When the transfer-type second substrate is stacked, as described with reference to FIG. 6 and the like, in addition to the resin material (adhesive material) 71 for forming the light shield 254 and the fixing base 253, the gap material 72 is placed at an appropriate place. By applying a resin material 73 containing, the gap between the transfer mold and the transfer mold can be controlled, and the alignment of the transfer mold can be adjusted. As a result, it is possible to provide an optical switching device in which the emission-side optical fiber 251 and the light-receiving side optical fiber 252 can be accurately fixed at predetermined positions, and light can be turned on and off with high accuracy by the light shielding unit 254.
[0072]
Furthermore, although the above has described an optical switching device as an example, it is possible to provide the manufacturing method of the present invention also for a micro switching device that operates a medium other than light or a micro machine for other uses. Therefore, it is possible to mass-produce micromachines with high product accuracy at a low yield.
[0073]
【The invention's effect】
As described above, in the present invention, when a microstructure having a structure on the order of micron or submicron or less, such as an optical switching device having an optical element, is formed on a different substrate. By superposing two fine structure layers and applying a resin layer containing a gap material, while controlling the thickness of the third structure layer formed between them, the relative position of each structure layer can be accurately adjusted at the same time. A method of manufacturing in a bonded state is disclosed. Therefore, according to the present invention, a highly reliable and high-quality microstructure can be easily manufactured at low cost.
[Brief description of the drawings]
FIG. 1 is a diagram showing an outline of a projector using an image display device using evanescent light.
FIG. 2 is a diagram showing an outline of a video display device (switching device) using evanescent light.
FIG. 3 is a flowchart showing an outline of a manufacturing process of the switching device shown in FIG. 2;
4 is a diagram showing a manufacturing process of the optical switching device shown in FIG. 2, and is a diagram showing a state in which an actuator layer is formed on a first substrate. FIG.
5 is a diagram showing a manufacturing process of the optical switching device shown in FIG. 2, and is a diagram showing how a prism layer is formed on a second substrate. FIG.
6 is a diagram showing a manufacturing process of the optical switching device shown in FIG. 2, in which a first resin and a second resin containing a gap material are applied on the first substrate shown in FIG. 4; FIG.
7 is a diagram showing a manufacturing process of the optical switching device shown in FIG. 2, in which the first and second substrates are faced and combined to form a third structure layer. FIG.
8 is a diagram showing a manufacturing process of the optical switching device shown in FIG. 2, and is a diagram showing a state of pixel separation in units of optical switching elements. FIG.
9 is a diagram showing a manufacturing process of the optical switching device shown in FIG. 2, and is a diagram showing a state in which the optical switching device is obtained by forming a chip and removing the sacrificial layer. FIG.
FIG. 10 is a flowchart illustrating in more detail the process of forming the third structural layer according to the present invention.
11 is a diagram schematically showing a preparation process of the first and second resin layers shown in FIG.
12 is a plan view showing a state in which the first and second resin layers shown in FIG. 10 are applied onto a first substrate. FIG.
13 is a diagram schematically showing a state in which each substrate is set on a jig in a process of bonding the first and second substrates shown in FIG. 10; FIG.
14 is a view schematically showing a state in which each substrate shown in FIG. 13 is set in a jig and the resin on the substrate is heated and acclimated. FIG.
15 is a view schematically showing a state in which each substrate shown in FIG. 13 is set on a jig and bonded together. FIG.
16 is a diagram schematically showing a state in which the bonded substrate shown in FIG. 15 is pressed.
17 is an enlarged schematic view of a part of the pasted state shown in FIG. 16. FIG.
FIG. 18 is a diagram schematically showing a process using mold transfer, which is a different manufacturing method to which the present invention is applied.
FIG. 19 is a diagram schematically illustrating a state in which a resin material including a gap material according to the present invention is applied to substrates having different shapes.
FIG. 20 is a diagram showing an outline of the structure and operation of a micromachine optical switching device according to a method for manufacturing a microstructure of the present invention.
[Explanation of symbols]
1 Light guide
2 Illumination light
3 Optical elements (optical element layers)
4 Microprism (second structure)
5 V-type support structure (third structure)
6 Actuator part, 60 Actuator layer (first structure layer)
7 Upper electrode and spring structure
8 Lower electrode
10 Optical switching element
20 Semiconductor substrate (first substrate)
41 Support layer (third structural layer)
42 Prism layer (second structural layer)
50 Optical switching devices
55 Optical switching unit (image display device)
71 1st resin material
72 Gap material
73 Second resin material
75 Third resin material (seal material)
81 Transfer mold (second substrate)
96 Glass substrate (second substrate)
97 Release layer
99 Sacrificial layer
100 jig
105 Temperature controller
180 Projector device

Claims (14)

A microstructure that is formed into a chip by combining a first substrate having a first structure layer and a second substrate having a second structure layer so that the first and second structure layers face each other. A method of manufacturing a microstructure having a step of forming a third structure layer that is a part of
In the step of forming the third structural layer, the first resin layer serving as the third structural layer is applied so as to be sandwiched between the first and second structural layers, and the first and second structural layers are applied. Applying a second resin layer containing a gap material so as to be sandwiched between the first and second substrates without being sandwiched between the structural layers;
Adjusting the alignment of the first and second substrates so that the relative positions of the first and second structural layers are in a desired state;
Curing the first resin layer,
In the step of forming the third structural layer, subsequent to or simultaneously with the applying step, the first structural layer is sandwiched between the first and second substrates outside the first and second structural layers. And a method of manufacturing a microstructure including a step of applying a third resin layer so as to surround the second structure layer. A microstructure that is formed into a chip by combining a first substrate having a first structure layer and a second substrate having a second structure layer so that the first and second structure layers face each other. A method of manufacturing a microstructure having a step of forming a third structure layer that is a part of
In the step of forming the third structural layer, the first resin layer serving as the third structural layer is applied so as to be sandwiched between the first and second structural layers, and the first and second structural layers are applied. Applying a second resin layer containing a gap material so as to be sandwiched between the first and second substrates without being sandwiched between the structural layers;
Adjusting the alignment of the first and second substrates so that the relative positions of the first and second structural layers are in a desired state;
Curing the first resin layer,
The manufacturing method of the microstructure provided with the temporary fixing process which hardens a said 2nd resin layer before the process of hardening a said 1st resin layer.   3. The method for manufacturing a microstructure according to claim 2, wherein, in the temporary fixing step, the second resin layer is UV-cured, and in the step of curing the first resin layer, the first resin layer is thermally cured. .   4. The method for manufacturing a microstructure according to claim 3, wherein the first and / or second structural layer includes a metal layer.   3. The method for manufacturing a fine structure according to claim 1, wherein in the applying step, the second resin layer is applied so as to be sandwiched between at least three portions of the first and second substrates.   3. The method for manufacturing a fine structure according to claim 1, wherein in the applying step, the first and second structural layers are applied while avoiding alignment marks for aligning the first and second structural layers with desired positions.   3. The method for manufacturing a fine structure according to claim 1, wherein the gap material is a spherical member having a predetermined tolerance diameter.   3. The distance between the first and second substrates in the region according to claim 1 or 2, in the region of the first and / or second substrate to which the second resin layer is applied, in accordance with the size of the gap material. The fine structure manufacturing method in which the structure which makes the said 3rd structure layer into predetermined thickness is formed.   3. The method according to claim 1, further comprising a step of heating the second resin layer to increase the fluidity of the second resin layer before adjusting the alignment after the applying step. Manufacturing method of structure. 3. The chip structure according to claim 1, wherein a plurality of chip areas in which a plurality of fine structures are aggregated are formed by the first and / or second substrate by forming the third structural layer, and dicing in units of the chips. And having a process of
In the applying step, the microstructure is manufactured by applying the second resin layer to regions of the first and second substrates, which are cut off by dicing. In Claim 1 or 2, the 2nd structure layer is formed in the 2nd substrate on both sides of a exfoliation layer,
A method for manufacturing a microstructure including a step of peeling the second substrate after forming the third structural layer.   3. The method for manufacturing a fine structure according to claim 1, wherein at least a part of the second substrate is a part of the fine structure to be chipped.   3. The method for manufacturing a microstructure according to claim 1, wherein the second substrate is a substrate for mold transfer, and includes a step of peeling the second substrate after the curing step.   3. The method for manufacturing a fine structure according to claim 1, wherein the first structure layer includes a portion that functions as an actuator.

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