JP3109556B2 - Package structure three-axis acceleration sensor and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acceleration sensor for detecting the speed and acceleration of an object moving in free space, and it is possible to simultaneously detect accelerations in X, Y and Z directions perpendicular to each other by one sensor. It is an object of the present invention to provide a package structure three-axis acceleration sensor having a novel structure and a method of manufacturing the same.

[0002]

2. Description of the Related Art The confirmation of speed and acceleration information of a moving object has so far largely depended on a one-axis sensor that can detect only one axis direction, and therefore, the robot hand If these one-axis sensors are to be used as sensors for completely controlling the operation of small mechanical devices, it is necessary to control the operation in the X, Y, and Z axis directions at the same time. One-axis sensors must be combined and used. However, despite the miniaturization of single-axis sensors, arranging a plurality of such sensors in a narrow space involves considerable difficulty in layout due to the relationship with other mechanical devices. Rather, a problem arises in terms of weight reduction for smooth operation, and the range of use is naturally restricted, resulting in an obstacle to the automation promotion of various mechanical devices.

[0003] Therefore, development of a sensor capable of simultaneously detecting accelerations in three directions of X, Y, and Z axes has been attempted, for example, as disclosed in Japanese Patent Application Laid-Open No. 5-45377, "Acceleration Detection Method and Acceleration Sensor". A working portion is formed at the center of the annular Si substrate, the working portion supports the center of a weight body made of glass or the like, and has a thin annular flexible portion formed around the working portion. Is used as a diaphragm, and the gap between the fixed portion on the outer peripheral edge and the weight body is formed as a capacitance part by utilizing the fact that the weight body moves and changes due to the acceleration applied to the sensor. The change amount of the part is replaced by the change of the frequency by the transmission circuit, the movement amount of the electrode of the capacitance part is calculated based on the frequency corresponding to the change of each capacitance part, and the acceleration is detected from the movement amount. Such acceleration detection method has been proposed Rutotomoni, it has been proposed an acceleration sensor having a self diagnosis function incorporates a self-diagnosis coil and the magnetic body.

Further, Japanese Patent Application Laid-Open No. Hei 3-2535,
The invention of the present application includes three regions including an operation portion, a flexible portion, and a fixed portion, including the basic structure of the above-described invention, and may be caused by movement of a weight body formed below the operation portion. An acceleration sensor for detecting a change in electrical resistance of a resistance element from a mechanical deformation of a flexible portion to measure a change in acceleration and a method of manufacturing the acceleration sensor are disclosed. A method of manufacturing an acceleration sensor having a river structure and a thin portion as a diaphragm has also been developed.
From the technical matters shown in each of these known documents, at present, as a basic structure of an acceleration sensor, a change in acceleration due to movement of an object is replaced with a deformation amount of a substance, and these are electrically converted. That is, the technical idea of capturing a change in capacitance or a change in electric resistance and converting the electric signal to an electric signal for detection is already known.

[0005] However, in some specific acceleration sensors developed and proposed based on the above-mentioned known technical idea, the structure that must be processed in order to capture an electrical change is made of an extremely thin material. It is extremely inconvenient as an expensive silicon single crystal plate that cannot expect much mechanical strength, and is easily damaged during the manufacturing process in which processing such as wet etching, dry etching, or dicing saw cutting is repeated, In addition to having the drawback that the yield as parts is extremely poor, in consideration of handling as parts during the assembly stage, consideration of damage and positioning when attaching to the base and weights It is necessary to pay close attention to ensuring the accuracy, etc., which may reduce the work efficiency. It was those that suffer from.

The above-mentioned problems of these prior arts are:
A silicon single crystal part processed into a predetermined structure to be one component of the acceleration sensor is treated as an independent and separate part with respect to other parts that must be combined, as in many general mechanical devices. The problem was not caused by the result of being directly incorporated into the acceleration sensor assembly process. In other words, the overall structure of the acceleration sensor was not prioritized for the mechanism without considering the unique properties of the silicon single crystal material. The present invention changes the viewpoint from the prior art and manufactures an entire acceleration sensor suitable for the property of a fragile and expensive silicon single crystal substrate. We have been engaged in development and research on the process and the structure of the entire acceleration sensor that enables it, and have repeated many trials and errors. Fruit, but finally, that it has completed a process for preparing it and the package structure triaxial acceleration sensor having the structure as will be detailed below.

[0007]

The three-axis acceleration sensor having a package structure according to the present invention basically has a silicon single crystal layer having a cross-shaped flexible structure portion between a base plate and a silicon single crystal cover plate, and a silicon single crystal layer on the silicon single crystal layer. It has a structure in which a glass layer having a weight plate portion serving as a deformation operation element to a cross-shaped flexible structure portion is joined and integrated at a regulated location, and is realized by devising a processing process. The gist is a characteristic configuration to be performed.

[0008] That is, in a peripheral frame portion joined and integrated between a base plate and a cover plate, four lower electrode islands, a tip support portion and a center support portion, and a beam structure thin portion connecting them are provided. The cross-shaped flexible structure portion is formed by joining only the lower surface of each lower electrode island portion and the lower surface of the tip support portion or the lower surface of the center support portion of the cross-shaped flexible structure portion to the base plate surface. While being disposed, the weight plate portion on which the upper electrode layer is vapor-deposited on the back surface is joined or supported on the upper surface of the central support portion at the center of the back surface including the conducting portion of the upper electrode layer, or includes the conducting portion of the upper electrode layer. A package structure three-axis acceleration sensor that is joined to and supported on the upper surface of each of the tip support portions on the four sides on the back side and combined on the cross-shaped flexible structure portion and also disposed in the peripheral frame portion. .

More specifically, four lower electrode islands in a silicon single crystal layer are provided in a peripheral frame joined and integrated between a rectangular base plate and a silicon single crystal cover plate. A cross-shaped flexible structure portion, which is located in the cross-shaped gap between the four lower electrode islands and includes a tip support portion, a central support portion, and a beam structure thin portion connecting them, has an overall planar shape of approximately The lower surface of each lower electrode island portion and the lower surface of the tip support portion or the lower surface of the center support portion of the cross-shaped flexible structure portion are joined to the base plate surface. And 4 of the silicon single crystal layer
It has a planar shape that covers the entirety of the lower electrode islands, and on the back surface, there are four upper electrode islands corresponding to immediately above the lower electrode islands and a current-carrying part connecting them. The weight plate portion on which the upper electrode layer is deposited is joined to and supported by the center portion of the back surface including the current-carrying portion of the upper electrode layer on the upper surface of the central support portion, or the top surface of the back surface including the current-carrying portion of the upper electrode layer is contacted with the tip. The package structure is a three-axis acceleration sensor that is joined to and supported on the upper surfaces of the support portions and combined on the cross-shaped flexible structure portion, and is also arranged in the peripheral frame portion.

This basic configuration includes a package structure three-axis acceleration sensor having two configurations as described below. One of them is a rectangular frame plate, a silicon single crystal cover plate, a peripheral frame portion, four lower electrode islands inside thereof, and a cross-shaped gap between the four lower electrode islands. , And a silicon single crystal layer in which a cross-shaped flexible structure portion composed of a tip support portion, a center support portion, and a beam structure thin portion connecting them, each of which is separately formed, has a generally square-shaped arrangement in a generally planar shape. And four upper electrode islands corresponding to immediately above the lower electrode islands on the back surface of the silicon single crystal layer, the planar shape covering the entire four lower electrode islands. And a weight plate portion on which an upper electrode layer formed by patterning a current-carrying portion connecting them and a glass layer composed of a peripheral frame portion are interposed and formed. The lower surface of the peripheral frame, the lower surface of the island for each lower electrode, and the cross-shaped flexible structure Only the lower surface of the tip support portion and the upper surface of the central support portion protrudingly formed at the plane cross-shaped crossing portion of the cross-shaped flexible structure portion, including the conducting portion of the upper electrode layer of the weight plate portion in the glass layer Only the center part is bonded and supported respectively, while the silicon single crystal cover plate is bonded and supported only to the glass layer peripheral frame integrated on the peripheral frame of the silicon single crystal layer, and the base is A package structure in which signal extraction lead wires are connected to the lower surface of each lower electrode island portion and the lower surface of at least one tip support portion of the cross-shaped flexible structure portion through through holes formed in the plate, respectively. It is a sensor.

The other is formed on a rectangular base plate surface with a peripheral frame portion, four lower electrode islands inside the peripheral frame portion, and a cross-shaped gap between the four lower electrode islands. A silicon single crystal layer having a cross-shaped flexible structure portion including a tip support portion, a center support portion, and a beam structure thin portion connecting them, each of which is formed in a cross-sectionally flexible manner, has a generally flat-shaped arrangement. While mounting, only the lower surface of the peripheral frame portion, the lower surface of each lower electrode island, and the lower surface of the central support portion of the cross-shaped flexible structure portion in the silicon single crystal layer are joined and integrated with the base plate, On the silicon single crystal layer, the silicon single crystal layer has a planar shape that covers the entire four lower electrode islands, and the back surface thereof corresponds to the lower electrode islands. Four upper electrode islands and current-carrying parts connecting them are patterned Forming a glass layer comprising a weight plate portion on which a lower electrode layer is vapor-deposited and a peripheral frame portion, wherein the weight plate portion has a cross-shaped flexible structure portion on four sides on the back surface including the conducting portion of the upper electrode layer. The silicon single crystal cover joined and supported only on the glass frame peripheral frame integrated on the peripheral frame of the silicon single crystal layer. A package structure 3 in which a signal extraction lead wire is connected to the lower surface of each lower electrode island portion and the lower surface of the central support portion of the cross-shaped flexible structure portion through a through hole formed in the base plate while covering the plate. It is an axial acceleration sensor. The structure of the three-axis acceleration sensor having the above package structure can be realized only by a special manufacturing process including first to fifth steps as described below.

[First step] A predetermined rectangular silicon single crystal plate is etched from the front and back sides of a base plate having through holes at predetermined positions.
The peripheral frame portion, the lower electrode island portion, and the tip support portion in the cross-shaped flexible structure portion, the central support portion each have a regulated height relationship, and each is connected by a thin portion. A single-plate silicon single crystal substrate engraved in the shape of a square with a generally planar shape is placed, and the lower surface of each of the silicon single crystal substrates, the lower surface corresponding to the peripheral frame portion, and each lower electrode The lower surface of the portion corresponding to the island, and the lower surface of the tip support portion of the cross-shaped flexible structure, or only the lower surface of the central support portion, are joined to the base plate by anodic bonding or other means. Integrate.

In this process, the single-plate silicon single crystal substrate is efficiently formed as one of a plurality of silicon single-crystal substrates simultaneously formed from one silicon wafer. Then, each part is transferred on a single silicon wafer in an accurate multi-cavity arrangement,
By repeating known etching means over several orders, each is made into a single-plate silicon single crystal substrate having a predetermined structure. Each part of each of these single-plate silicon single crystal substrates, that is, a portion corresponding to a peripheral frame portion serving as a peripheral frame portion in a final structure, a portion corresponding to a lower electrode island portion serving as a lower electrode island portion, a cross-shaped flexible member The structures of the tip strut portion and the center strut equivalent portion serving as the tip strut portion and the center strut portion in the structural portion, and the thin-walled portion remaining therebetween must be realized by the following relationship.

That is, on the upper surface side of the single-plate silicon single crystal substrate, the upper surface of the portion corresponding to the peripheral frame portion and the portion corresponding to the central support portion in the cross-shaped flexible structure portion basically have a single-plate shape. Is a portion that remains as the upper surface of the silicon single crystal substrate in the shape of a silicon and is not eroded by etching, and is formed to be slightly thinner, for example, about 10 μm thinner. Four lower electrode island portions, each of which is independently formed in a symmetrical arrangement in the corresponding portion, and four lower end pillar portions of the cross-shaped flexible structure portion which are lower than the four island portions. A part is formed.

The lower surface side has a cross-shaped flexible portion among the above-described portions corresponding to the upper surface side, that is, a portion corresponding to the peripheral frame portion, a portion corresponding to the lower electrode island portion, and a portion corresponding to the cross-shaped flexible structure portion. The other portion is slightly etched and the thickness is substantially the same, for example, about 20 microns except for the lower surface portion of the structural portion corresponding portion except for the lower surface of the central support portion portion (ie, the lower surface of the silicon wafer). A thinned portion is formed by shaving off, and a portion opposed to a portion etched to be the lowest on the upper surface side is a thin portion. The thickness of the thin portion is, for example, approximately 30 μm. It is said. In this etching process on the lower surface side, a very important portion is a portion related to an etching width for leaving a portion corresponding to a lower surface of a portion corresponding to a peripheral frame portion formed on the upper surface side. That is, the width left as a lower surface of the portion corresponding to the peripheral frame portion on the upper surface side must be controlled to be equal to or less than half the width of the corresponding portion of the peripheral frame portion on the upper surface side.

In the single-plate silicon single crystal substrate thus formed, the planar shape formed by the contours of the portions corresponding to the portions engraved in a regulated relationship has a shape similar to a substantially square-shaped character. Then, the national structure of the cross-shaped cross section is equivalent to the peripheral frame, the cross in the middle is the cross-section corresponding to the column and the vertical and horizontal ends of the column, and finally the cross-shaped flexible structure The portion forming the cross-shaped flexible structure portion corresponding to the above, and the four grid portions divided by the portions become the portion corresponding to the island portion for the lower electrode, and the thin portion is formed between the corresponding portions. The whole structure is maintained as a single plate.

The single-plate silicon single crystal substrate formed in advance as described above has a lower surface corresponding to a peripheral frame portion therein.
The lower surface of each lower electrode island-corresponding portion and the cross-shaped flexible structure portion-corresponding flat cross-shaped four tip support portions at each tip (the lower surface of the cross-shaped flexible structure portion-corresponding central pillar portion-corresponding lower surface) Are bonded and integrated on the base plate surface by anodic bonding means or the like. These steps also involve a plurality of single-crystal silicon substrates having a predetermined structure. A silicon wafer arranged in a single piece is bonded and integrated on a base plate surface having substantially the same shape as the silicon wafer without being cut and divided into individual silicon single crystal substrates. It is efficient and convenient.

On the other hand, the base plate employed here is composed of four tip pillars which are paired in advance in the vertical or horizontal direction in the four lower electrode island individual lower surfaces and the cross-shaped flexible structure. 5 convenient locations for at least one of the parts, optimally 6
It is a glass plate with perforations leading to various places. In addition,
The four end strut portions corresponding to the four ends of the plane cruciform portion of the cruciform flexible structure portion to be processed in this step, and the central strut portion corresponding to the center cruciform crossing portion are as described above. In addition to the basic processing, those having a structure formed by the following processing are also included.

That is, in the etching process on the upper surface side and the lower surface side of the silicon single crystal substrate, the portion corresponding to the central support portion is:
The projection is formed only on the upper surface from the thin portion (therefore, a portion corresponding to the central support portion is not formed below the thin portion). The lower surface side is processed to remain as the lower surface of the silicon single crystal substrate as it is,
Conversely, the central strut portion is formed so as to protrude only to the lower surface from the thin portion (therefore, a portion corresponding to the central strut portion is not formed on the thin portion). The portion corresponding to the portion has a structure in which the upper surface side is left as the upper surface of the silicon single crystal substrate as it is, and the lower surface side is raised above the lower surface of the silicon single crystal substrate. A manufacturing process for realizing a configuration corresponding to the above, and a structure by processing such as the latter is a manufacturing process for realizing a configuration corresponding to the claim 3.

[Second Step] After a single-plate silicon single crystal substrate having a predetermined structure is bonded and integrated on the base plate surface as described above, anisotropic dry etching is performed.
In the silicon single crystal substrate, each portion between the portion corresponding to the peripheral frame portion and the portion corresponding to the inside thereof, and the portion between the outer periphery of the portion corresponding to the flat cross-shaped flexible structure and the portion corresponding to the island portion for the lower electrode. A peripheral frame portion integrated on a base plate by removing a thin portion, four lower electrode islands on the inside thereof, and a cross-shaped flexible structure located between the four lower electrode islands The parts are separated into individual independent components, and several component blocks made of silicon single crystal are placed on the base plate in an orderly relationship from a single-crystal silicon substrate This is a step of processing and forming a silicon single crystal layer that is arranged and integrated.

The thin portion left in this step is composed of a central support portion formed at the intersection of the cross-shaped flexible structure portion and four tip support portions formed at each of the vertical and horizontal ends of the cross shape. As a result, only the thin portion extending between the four front-end struts and the central strut extending from the four end struts, or a structure corresponding to the billing opening 3 formed in a converse structure, is used. The thin portion extending in all directions from the support portion to the tip support portion forms a beam structure thin portion with a cantilever structure for each tip support portion or the central support portion,
A delicately deformable structure is realized by the acceleration of gravity applied from the weight plate portion combined in the third and fourth steps to be described later, which is applied to the center support portion or the tip support portion.

[Third Step] On the silicon single crystal layer formed integrally by the above steps, a planar shape which covers the entire silicon single crystal layer in advance, and the surface side of which is finally a peripheral frame portion After placing a glass plate that is processed lower than the frame plate equivalent part, the weight plate part equivalent part that eventually becomes the weight plate part,
The glass plate is formed with a central support portion protruding from the peripheral frame portion and the cross-shaped cross portion of the cross-shaped flexible structure portion in the silicon single crystal layer. Are the four tip support portions) After being integrated only on each upper surface, the boundary between the peripheral frame portion equivalent portion and the weight plate equivalent portion of the glass plate regulated to the position overlapping the peripheral frame portion of the silicon single crystal layer, The glass layer composed of the peripheral frame portion and the weight plate portion separated from the peripheral frame portion is formed by performing groove cutting with a dicing saw so that the groove reaches the middle of the peripheral frame portion of the silicon single crystal layer. Form. However, at this stage,
The weight plate portion has not yet achieved a structure supported only by the cross-shaped flexible structure portion.

The glass plate has, on its back surface, a portion corresponding to the portion immediately above the lower electrode island portion in the silicon single crystal layer.
The upper electrode layer having a pattern in which each of them is an upper electrode island portion, and the upper electrode layer in such a manner that each of the upper electrode island portions becomes an energizing portion for energizing at the center of the back surface, must be previously deposited and formed. When bonded on the silicon single crystal layer laminated and integrated in the process, the current-carrying portion of the upper electrode layer formed on the back surface of the glass plate is a cross-shaped flexible structure portion that can be placed on the silicon single crystal layer. 4. The central support portion, which is positioned correctly on the upper surface of the central support portion protrudingly formed at the plane cross-shaped cross section, is energized with respect to the central support portion.
In the configuration corresponding to the above, the current-carrying portions are located on the four tip-post-shaped surfaces so as to be energized to each tip-post, and each upper-electrode island in the upper electrode layer is At a predetermined planned interval below the lower electrode islands, the silicon single crystal layers are opposed to each other just above the corresponding lower electrode islands.

A particularly important part in this step is a grooving process at a predetermined position of the glass plate by a dicing saw which is performed after the bonding and integration of the glass plates. It is restricted to the position where the frame is hung, in other words, the peripheral frame portion of the silicon single crystal layer under the glass plate is also grooved, and the groove reaches the middle of the peripheral frame portion of the silicon single crystal layer. When the grooving process is performed at this restricted place, cutting chips and cooling water generated in the process are the most important components of the sensor of the present invention. It is possible to completely prevent the post-processing from being impossible between the upper and lower electrode islands and the cross-shaped flexible structure.

At this stage, the glass plate itself is separated into a peripheral frame portion and a weight plate portion inside the peripheral frame portion, and it is possible to realize a state in which they are temporarily formed on a glass layer which independently forms a layer. However, the grooves formed by the above-mentioned grooving process have an optimum thickness in the middle of the peripheral frame portion in the silicon single crystal layer, and optimally for a dry etching process to be performed for the same location in a subsequent process. (Slightly thinner than the maximum value that can be processed, the minimum thickness that will not break) is left at the part where it is left. Since a part of the peripheral frame portion of the silicon single crystal layer is continuous, the final weight plate portion still supported only by the upper end of the pillar portion of the cross-shaped flexible structure portion in the silicon single crystal layer The structure has not been realized.

[Fourth Step] The silicon single crystal material below the groove in the peripheral portion of the silicon single crystal layer left by the grooving in the above step is completely penetrated by anisotropic dry etching, The inner part of the single crystal layer frame is
Separated on the lower surface of the outer periphery of the weight plate portion of the glass layer, and processed into a suspended structure, the peripheral frame portion of the glass layer is continuous and integrated vertically on the peripheral portion of the silicon single crystal layer. After the formation, the silicon single crystal cover plate is integrally covered with only the upper surface of the glass layer peripheral frame portion as a bonding portion.

According to this step, for the first time, the weight plate portion in the glass layer is the upper end of the central support portion of the cross-shaped flexible structure portion in the silicon single crystal layer, or four tips in the structure according to claim 3. The final structure supported by only one of the upper ends of the strut portions is realized, and the weight of the weight plate portion and the acceleration due to its gravity are reduced by the central strut portion of the cross-shaped flexible structure portion or the four tip ends. Through the pillars, a structure is formed that transmits to the beam structure thin portion extending in a cross shape from them, and the upper electrode islands and the lower electrode islands that constitute the detection unit indispensable in the present invention are formed. A structure in which the center or four sides of the weight plate portion is supported by the center support or the four end supports of the cruciform flexible structure is realized at a predetermined interval. A single crystal cover plate is covered and a sensor with a package structure between the bottom layer and the base plate, that is, a structure that does not require cutting chips or moisture to enter or remove them at the manufacturing stage. Will be done.

[Fifth Step] If a signal extraction lead wire is connected to a through hole previously formed in the base plate which is the lowermost layer of the package structure laminated and integrated as described above, The package structure three-axis sensor of the present invention is completed. It is to be noted that a silicon wafer in which a plurality of single-unit silicon single-crystal layers are taken as an efficient manufacturing method is adopted, and the layers are sequentially adapted to each layer, and the layer structure is sequentially advanced. In the case of the production method of cutting and separating each time, it is sequentially laminated on the base plate,
It is necessary to perform a process of cutting and separating the whole by using a dicing saw in accordance with the outer peripheral contour of the sensor for each unit composed of the integrated silicon single crystal layer, glass layer and silicon single crystal cover plate having a predetermined structure. Hereinafter, the package structure three-axis acceleration sensor of the present invention and a method of manufacturing the same will be described in detail with reference to specific examples.

[0029]

Embodiment 1 The embodiment shown in the exploded perspective view of FIG. 1 and the main part perspective view including a partial cross section and a broken cross section of FIG.
The package-type three-axis acceleration sensor according to the present embodiment has a configuration in which the overall shape is, for example, about 8 mm square in a plane shape and about 1 mm in thickness. Each of the layers constituting the package structure of the base plate 1, the silicon single crystal layer 2, the glass layer 3, and the silicon single crystal cover plate 4 has a thickness of 0.3 from the bottom. Ultra-thin materials such as around millimeters will be adopted, and the strength of each material will be extremely fragile, requiring the latest attention to handling.Therefore, it has been proposed by the conventional manufacturing method until then. It can be said that the product yield was necessarily inferior when trying to realize a sensor having the above structure.

In this embodiment, a through hole for a lead wire is formed by restricting a portion of the silicon single crystal layer 2 to be covered by the lower electrode island 21 and the tip support 23, which will be described later. The peripheral frame 25 of the silicon single crystal layer 2 and the peripheral frame 32 of the glass layer 3 are vertically joined on the peripheral edge of the square base plate 1 having 11, 11,...
Integrally forming a peripheral frame which is connected vertically in the cross section, and the lower electrode island portion 21 in the silicon single crystal layer 2 and the tip support portion 23 and the central support portion 22 are connected inside the peripheral frame. The cruciform flexible structure comprising the beam structure thin portion 24 is joined to and integrated with the base plate 1 in an arrangement regulated so as to have a substantially cross-shaped arrangement. The center of the back surface of the weight plate portion 31 of the glass layer 3 is disposed on the upper surface of the central support portion 22 in the cross-shaped flexible structure so as to be joined and supported.

As shown in the exploded view of FIG. 1, the back surface of the weight plate portion 31 is directly above the lower electrode island portion 21 in the cross-shaped flexible structure portion of the silicon single crystal layer 2 in advance. Upper electrode islands 41, 41,... Arranged at corresponding positions.
The upper electrode layer 4 is formed by means of vapor deposition, printing, or the like, and is formed by a means such as vapor deposition or printing, and a central support portion in the cross-shaped flexible structure portion of the silicon single crystal layer 2. 22 is electrically connected to the lower electrode island portion through the thin beam portion 24 of the cross-shaped flexible structure portion, the tip support portion 23, and the signal extraction lead wire connected to the lower surface thereof. The amount of movement of the weight plate portion 31 is calculated based on a change in the capacitance between the weight plate 21 and the weight of the weight plate portion 31, and then the acceleration is detected and incorporated into a circuit of a calculation device.

The upper surface of the weight plate portion 31 is formed lower than the upper surface of the peripheral frame portion 32 in the glass layer 3.
In itself, there is no contact portion except that the center of the back surface is supported by the central support portion 22, and the lower portion of the silicon single crystal cover plate 5 joined to the upper surface of the peripheral frame portion 32 in the glass layer 3 and the peripheral frame portion 32 A structure capable of receiving the acceleration of gravity due to the action from the outside over a range of 360 degrees in the space surrounded by.

[0033]

Second Embodiment Next, a description will be given of an embodiment having a configuration corresponding to claim 3 shown in an exploded perspective view of FIG. 3 and a perspective view of a main part including a partial cross section and a broken cross section of FIG. Then, this is a typical case in which the supporting structure of the weight plate portion 31 is different from that in the first embodiment, that is,
The peripheral frame 25 of the silicon single crystal layer 2 and the peripheral frame 32 of the glass layer 3 are vertically mounted on the peripheral edge of the square base plate 1 having the through holes 11, 11,... To form a peripheral frame connected vertically in the cross-section, and the lower electrode island portion 21 of the silicon single crystal layer 2, the tip support portion 23 and the central support portion 22 inside the peripheral frame.
A cross-shaped flexible structure composed of a beam structure thin portion 24 connecting them has an arrangement regulated so as to have a substantially cross-shaped arrangement,
It is bonded and integrated on the base plate 1, and the back surface of the weight plate portion 31 of the glass layer 3 is bonded to the upper surface of the four sharp support portions 22 in the cross-shaped flexible structure portion of the silicon single crystal layer 2. , So that they are supported.

As shown in the exploded view of FIG. 1, the back surface of the weight plate portion 31 is directly above the lower electrode island portion 21 in the cross-shaped flexible structure portion of the silicon single crystal layer 2 in advance. Upper electrode islands 41, 41,... Arranged at corresponding positions.
The upper electrode layer 4 is formed by means of vapor deposition or transfer or the like, and is formed by means of vapor deposition or transfer. By being electrically connected to at least any one of the above, the beam structure thin portion 24 of the cross-shaped flexible structure portion, the central support portion 23, and the lead wire 5 connected to the lower surface thereof, Similarly to the first embodiment, the acceleration is incorporated in a circuit of an arithmetic unit for detecting the acceleration.

[0035]

Embodiment 3 The structure of the package type three-axis acceleration sensor of the present invention formed as described above is realized by the following characteristic manufacturing process (corresponding to claim 2). It is. That is, a single-plate-shaped silicon single crystal substrate engraved in a substantially rectangular cross-section in the overall plane shape having the structure shown in FIG. As shown in FIG. B, the silicon single crystal substrate is placed on a base plate 1 in which through holes 11, 11,... The lower surface of the peripheral frame portion-equivalent portion 25a, the lower electrode island-equivalent portions 21a, 21a,..., The lower surface, and the tip support portions 23a, 23 of the cross-shaped flexible structure portion
a, a first step of bonding and integrating only the lower surface to the base plate 1 by anodic bonding or other means;

Although not shown in the drawing, nine single silicon single crystal substrates in this step are simultaneously transferred to a single silicon wafer so as to be formed at correct positions on one silicon wafer. In the last stage after the base plate 1, the silicon single crystal layer 2, the glass 3, and the silicon single crystal cover plate 5 are accurately laminated and integrated, and cut one unit at a time. What is obtained by the embodiment which is formed into a finished product is shown as one unit for convenience. Further, each part of the single plate-shaped silicon single crystal substrate of each unit body, that is, a peripheral frame portion equivalent portion 25a which becomes the peripheral frame portion 25 in the final structure, and a lower electrode island portion which becomes the lower electrode island portion 21 Part 21a, a tip strut portion 23a and a center strut equivalent portion 22a to be the tip strut portion 23 and the center strut portion 22 in the cross-shaped flexible structure portion, and the beam structure thin portion 24 remaining therebetween.
Is formed in the relationship described in the section describing the basic configuration.

After a single-plate silicon single crystal substrate having a predetermined structure is bonded and integrated on one surface of the base plate as described above, anisotropic dry etching is performed on the silicon single crystal substrate. The thin portions between the peripheral frame portion 25a and the corresponding portions on the inner side thereof, and between the outer periphery of the flat cross-shaped cross-shaped flexible structure portion and the lower electrode island portion 21a are removed. The peripheral frame 25 integrated on the base plate 1, the four lower electrode islands 21 inside thereof, and the cross-shaped flexible structure located between the four lower electrode islands 21 However, from the single-crystal silicon single-crystal substrate that had been separated into individual components, several single-crystal silicon component blocks were placed on the base plate in a regulated relationship. It is processed and formed into a silicon single crystal layer 2 that is arranged and integrated. The second step.

As a result, the center support portion 22 formed at the intersection of the cross-shaped flexible structure portion and the four front-end support portions 23, 23,. Only the thin portion between the two remains, and the beam structure thin portion 24, 24,...
, A beam-structure thin portion 24 extending from each of the four end support portions 23, 23,.
.. Have a cantilever structure with respect to each of the tip support portions 23, 23,.
And a structure that can be delicately deformed by the acceleration of gravity from the weight plate portion 31 combined in the third and fourth steps described later.

On the silicon single crystal layer 2 integrally formed in the second step, as shown in FIG. 5D, the silicon single crystal layer 2 has a planar shape which covers the entire silicon single crystal layer 2 in advance, and the front side is finally formed as a peripheral frame. A glass plate obtained by etching a lower portion of the weight plate portion 31a that eventually becomes the weight plate portion 31 than the peripheral frame portion equivalent portion 32a that becomes the portion 32 is placed, and the glass plate is
The peripheral frame 25 of the silicon single crystal layer 2 and the central support 22 protruding from the plane cross-shaped intersection of the cross-shaped flexible structure are integrated only on the upper surfaces of the silicon single crystal layer 2, respectively. The boundary between the peripheral frame portion equivalent portion 32a and the weight plate portion equivalent portion 31a of the glass sheet regulated to the position where the portion extends over the portion 25 is grooved by a dicing saw, and the groove 3 is formed.
The fourth step is to form the glass layer 3 composed of the peripheral frame part 32 and the weight plate part 31 separated therefrom by making the metal element 4 reach the middle of the peripheral frame part 25 of the silicon single crystal layer 2. .

As shown in the figure, the weight plate portion 3
1a is a structure in which the peripheral frame portion 25 of the silicon single crystal layer 2 joined to the peripheral back surface is connected below the groove 34, and the groove 34 is connected to the peripheral frame portion 25 of the silicon single crystal layer 2; Further, since the space does not communicate with the space on the side of the cross-shaped flexible structure portion, the processing in this step can be performed without any processing waste, cooling water, and the like during dicing in this step entering the space. In the glass plate used in this step, four pieces corresponding to immediately above the lower electrode islands 21, 21,. ,……age,
The upper electrode layer 4 having a pattern in which each of the upper electrode islands 41, 41,... Becomes a current-carrying portion 42, 42,. . In the figure, reference numeral 26 denotes a small protrusion which regulates the downward displacement of the weight plate portion 31 formed on the lower electrode island portion 21 of the silicon single crystal layer 2, and 33 designates the upward displacement. The small protrusions formed on the surface of the weight plate portion 31 itself for regulation are shown in each etching process.

The silicon single crystal material below the groove in the peripheral portion of the silicon single crystal layer left by the grooving in the third step is completely penetrated by anisotropic dry etching to form a silicon single crystal layer. The inner portion of the peripheral frame portion 25 is separated into the lower surface of the outer periphery of the weight plate portion 31 of the glass layer 3 and is processed into a suspended structure as shown in FIG. After the glass layer peripheral frame part 32 is formed on the peripheral frame part 25 to have a structure in which the glass layer peripheral frame part 32 is continuous and integrated vertically and integrally, the silicon single crystal cover plate 5 is formed by using only the upper surface of the glass layer peripheral frame part 32 as a bonding part. A fourth step of integrally covering with As a result, the weight plate portion 31 in the glass layer 3
Realizes a final structure supported only by the upper end of the central support portion 22 in the cross-shaped flexible structure portion of the silicon single crystal layer 2, and the weight of the weight plate portion 31 is reduced by the cross-shaped flexible structure portion. Through the central support portion 22 of this embodiment, the structure is transmitted to the silicon single crystal beam structure thin portion 24 extending in a cross shape therefrom.

.., And 12 previously drilled in the base plate 1, which is the lowermost layer of the package structure laminated and integrated as described above, lead wires 6 for signal extraction. The fifth step of connecting 6,... Prior to the step of connecting the lead wires 6, 6,..., The base plate 1 including the through holes 11, 11,. Every
This step is performed by soldering one end of the lead wire 6 to the same place. Finally, a plurality of silicon wafers are taken, and the above-described manufacturing process is sequentially performed. After that, the wafers are cut and separated into one unit by a dicing saw, and the base plate is separated. 1. A package type three-axis acceleration sensor of the present invention in which a silicon single crystal layer 2, a glass layer 3, an upper electrode layer 4, and a silicon single crystal cover plate 5 formed in a predetermined structure are stacked and packaged on 1 is completed.

[0043]

The package-type three-axis acceleration sensor of the present invention manufactured as described above is incorporated in a robot or other automatic machine for various uses, and moves the machine itself or each component constituting the machine. With the change in acceleration accompanying with the above, a gravitational acceleration is applied to the weight plate portion 31 of the glass layer 3 which is a detection portion in the sensor, and this is the silicon single crystal beam structure thin portions 24 of the same cross-shaped flexible structure portion. , ……
Act as an external force to cause a sensitive bending phenomenon, so that the relative position of the weight plate portion 31 itself to the silicon single crystal layer 2 changes in a horizontal plane in conjunction with the bending. As a result, the upper and lower relative positions of the upper electrode islands 41, 41,... With respect to the lower electrode islands 21, 21,. Change, causing a change in the gap between the two,
The change in capacitance corresponding to the change in the gap is captured, converted into an electric signal and detected, and the arithmetic circuit is used to accurately detect the three-axis acceleration of the object such as a machine or a component from the value. Things.

As described above, the package structure triaxial sensor of the present invention, which operates extremely sensitively and accurately, comprises the island 21 for the lower electrode constituting the silicon single crystal layer 2, the tip support 23 and the center support 22, Thin section 2 connecting beams
Before the cross-shaped flexible structure portion 4 is realized, the portion corresponding to the lower electrode island portion 21a, the tip support portion portion 23a and the center support portion 22a, and a thin wall connecting them A required portion of a single-plate silicon single crystal substrate, which has been etched so as to correspond to a cross-shaped flexible structure portion composed of a silicon substrate, is joined to the base plate 1 to secure a hard-to-break state. The structure of each part of the silicon single crystal layer, which is extremely thin and fragile, is realized by a characteristic manufacturing method in which processing of the crystal substrate itself and processing combined with the glass layer 3 bonded thereon are performed. However, it is extremely safe, accurately formed, and manufactured through a characteristic process.Therefore, there is a considerable probability that processing waste etc. will enter defective parts during the process and become defective. Therefore, a highly reliable sensor can be obtained at a high yield, and an excellent effect that it becomes extremely easy to adopt the sensor as a three-axis sensor for various uses can be obtained. .

These effects are obtained by processing a silicon single crystal plate into a fine shape, performing dicing at the initial stage of joining glass or forming a weight, and performing dry etching at the final process. The package-type three-axis acceleration sensor is a three-axis acceleration sensor that employs a detection unit having a crossed flexible structure structure. From a structural point of view, compared to the conventional diaphragm structure, a three-axis sensitivity can be made stable and stable, and a highly reliable sensor can be realized.
Base plate 1 that functions as a reinforcement and protection plate even during the manufacturing process
In addition, the cover plate 5 serves as a package-type sensor that covers the detection unit, thereby realizing a more reliable structure.

In particular, the package type three-axis acceleration sensor having the structure disclosed in each of the embodiments can be most effectively implemented by the manufacturing method, and the above-mentioned features are more remarkably exhibited. In addition, the manufacturing method of the embodiment also has the effect of increasing the manufacturing efficiency of making it possible to manufacture a plurality of sensors collectively, so that there is also a practical advantage that stable supply of highly accurate sensors becomes possible. It will be combined. As described above, the present invention enables a three-axis acceleration sensor excellent in function and structure to be efficiently and stably realized by a characteristic manufacturing method. It is expected that it will be very effective for further automation of the device.

[Brief description of the drawings]

The drawings show only some of the representative embodiments of the present invention.

FIG. 1 is an exploded perspective view of a package type three-axis acceleration sensor of the present invention.

FIG. 2 is a perspective view including a partial cross section in which the peripheral frame portion is omitted and partially cut away.

FIG. 3 shows a package mold 3 according to another embodiment of the present invention.
It is an exploded perspective view of an axis acceleration sensor.

FIG. 4 is a perspective view including a partial cross section in which the peripheral frame portion is omitted and partially cut away.

FIG. 5 is a cross-sectional view at a main process step for explaining a manufacturing process.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Base plate 11 Same through hole 12 Same through hole 2 Silicon single crystal layer 21 Same lower electrode island part 21a Same lower electrode island part 22 Same center support part 22a Same center support part equivalent part 23 Same tip support part 23a Equivalent portion of the same end support portion 24 Thin portion of the same beam structure 24a Thin portion of the same beam structure 25 Same peripheral frame portion 25a Same peripheral frame portion 3 Glass layer 31 Same weight plate portion 32 Same peripheral frame portion 4 Upper electrode layer 41 Upper electrode island 42 Same conducting part 5 Silicon single crystal cover plate 6 Lead wire

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Atsushi Watanabe No. 683 in front of Namaki-shaped car in Yamagata City Inside Yamagata Industrial Technology Center (72) Inventor Ikutaro Nakagawa 683 in front of Numaki-shaped car in Yamagata City Yamagata Prefecture Inside the Industrial Technology Center (72) Inventor Seiya Kobayashi 683 in front of Numaki-shaped car in Yamagata City Inside Yamagata Prefecture Industrial Technology Center (72) Inventor Takashi Mineta 683 in front of Numaki-shaped car in Yamagata City Yamagata Prefecture Inside the Industrial Technology Center (72) Inventor Yoshiyuki Watanabe No. 683 in front of Numaki-shaped car in Yamagata City Inside the Yamagata Industrial Technology Center (56) References JP-A-6-18552 (JP, A) JP-A-4- 278464 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H01L 29/84 G01P 15/125

Claims (5)

(57) [Claims] In a peripheral frame portion joined and integrated between a base plate and a cover plate, four lower electrode islands, a tip support portion and a center support portion, and a beam structure thin portion connecting them are provided. The cross-shaped flexible structure portion consisting of:
And only one of the lower surface of the tip support portion or the lower surface of the central support portion of the cross-shaped flexible structure portion is disposed on the base plate surface, and the weight plate portion on which the upper electrode layer is vapor-deposited on the back surface has an upper portion. A cross shape is formed by joining and supporting the upper surface of the central support portion at the center of the back surface including the conducting portion of the electrode layer, or by joining and supporting the upper surface of the tip support portion at each of the back surfaces including the conducting portion of the upper electrode layer. A package structure three-axis acceleration sensor combined with a flexible structure part and also arranged in a peripheral frame part. 2. Four lower electrode islands in a silicon single crystal layer and four of them in a peripheral frame joined and integrated between a rectangular base plate and a silicon single crystal cover plate. The cross-shaped flexible structure portion, which is located in the cross-shaped gap portion of the lower electrode island portion and includes the tip support portion, the central support portion, and the thin-walled portion connecting the beams, has an overall planar shape substantially in the shape of a cross. Only the lower surface of the lower electrode island portion in each of these portions and the lower surface of the tip support portion or the lower surface of the central support portion of the cross-shaped flexible structure are joined to the base plate surface. And has a planar shape that covers the entire four lower electrode islands in the silicon single crystal layer, and has four back surfaces corresponding to directly above the lower electrode islands on the back surface thereof. Weight with upper electrode layer consisting of upper electrode islands and current-carrying parts connecting them The plate portion is joined to and supported on the upper surface of the central support portion at the center of the back surface including the conducting portion of the upper electrode layer,
Alternatively, a package structure which is joined to and supported on the upper surface of each of the tip support portions on the four sides on the back surface including the current-carrying portion of the upper electrode layer to be combined with the cross-shaped flexible structure portion and similarly arranged in the peripheral frame portion 3-axis acceleration sensor. 3. A cross-shaped gap between a rectangular base plate and a silicon single crystal cover plate, a peripheral frame portion, four lower electrode island portions inside the peripheral frame portion, and the four lower electrode island portions. A single silicon crystal in which a cross-shaped flexible structure portion formed of a tip support portion, a center support portion, and a beam structure thin portion connecting them is separated from each other, and the entire plane is arranged in a generally square shape. Layer, and four upper electrode islands corresponding to immediately above the lower electrode islands on the back surface of the silicon single crystal layer, the planar shape covering the entire four lower electrode islands. A weight plate portion on which an upper electrode layer formed by patterning a portion and a current-carrying portion connecting each of them is deposited and a glass layer composed of a peripheral frame portion are interposed and formed. Of the lower frame, the lower surface of the island for each lower electrode, and the cross-shaped flexible structure. Only the lower surface of each tip support, and
Only the center of the back surface including the conducting portion of the upper electrode layer of the weight plate portion in the glass layer is joined and supported with respect to the upper surface of the central support portion protruding from the cross-shaped cross portion of the cross-shaped flexible structure portion. On the other hand, the silicon single crystal cover plate is bonded and supported only to the peripheral frame portion of the glass layer integrated on the peripheral frame portion of the silicon single crystal layer, and has a through hole formed in the base plate. A three-axis acceleration sensor having a package structure in which signal extraction lead wires are respectively connected to the lower surface of each lower electrode island portion and the lower surface of at least one tip support portion of the cross-shaped flexible structure portion through the same. 4. A rectangular support plate, a peripheral frame portion, four lower electrode islands on the inner side thereof, and a cross-shaped gap between the four lower electrode islands, and a tip support. Cross-shaped flexible structure portion consisting of a portion, a central support portion and a beam structure thin portion connecting them are placed on each other, and a silicon single crystal layer in which the entire plane formed by separating and forming the respective portions is substantially in a U-shape is placed. Only the lower surface of the peripheral frame portion, the lower surface of each island for lower electrodes, and the lower surface of the central support portion of the cross-shaped flexible structure portion in the silicon single crystal layer are joined and integrated with the base plate, while the silicon single crystal layer is Has a planar shape that covers the entire four lower electrode islands of the silicon single crystal layer, and the four upper electrodes corresponding to the upper portions of the lower electrode islands on the back surface thereof. The upper electrode layer was formed by patterning the islands and the conducting parts connecting them. A glass layer composed of a weight plate portion and a peripheral frame portion is formed, and the weight plate portion is formed on the upper surface of the four tip support portions of the cross-shaped flexible structure portion on the four sides of the back surface including the conducting portion of the upper electrode layer. Joined and supported, and further covered with a silicon single crystal cover plate joined and supported only on the glass layer peripheral frame integrated on the peripheral frame of the silicon single crystal layer, A three-axis acceleration sensor having a package structure in which signal extraction lead wires are respectively connected to the lower surface of each lower electrode island and the lower surface of a central support of a cross-shaped flexible structure through through holes formed in a base plate. 5. A portion corresponding to a peripheral frame portion and a lower electrode are formed by etching a predetermined rectangular silicon single crystal plate from the front and back on a base plate having through holes formed at predetermined positions in advance. In the overall planar form, the island portion equivalent portion, the tip support portion in the cross-shaped flexible structure portion, and the central support portion each have a regulated height relationship, and each is connected by a thin portion. A single-plate silicon single crystal substrate engraved in the shape of an approximate square is placed, and a lower surface corresponding to a peripheral frame portion, a lower surface corresponding to an island portion for each lower electrode, and a lower surface of the silicon single crystal substrate, and A first step of joining and integrating only the lower surface of each of the end support portions or the lower surface of the central support portion of the cross-shaped flexible structure with the base plate by anodic bonding or other means. By anisotropic dry etching, in the silicon single crystal substrate integrated in the above step, between the peripheral frame equivalent portion and the corresponding portions inside thereof, and the outer periphery of the flat cross-shaped flexible structure equivalent portion. The peripheral portion integrated on the base plate, the four lower electrode islands, and the four lower electrode islands are removed by removing the thin portions between the lower electrode island equivalent portions. A second step of forming a silicon single crystal layer in which a cross-shaped flexible structure portion located in a gap portion of the portion is formed so as to have a generally flat cross-sectional shape formed by separating and forming respective portions of each portion. On the silicon single crystal layer integrally formed by the above steps, a planar shape covering the entire silicon single crystal layer, and on the back surface,
An electrode layer is formed by patterning four upper electrode islands corresponding directly above the lower electrode islands and a current-carrying part connecting the upper electrode islands, and the front surface side is equivalent to the same peripheral frame part. A glass plate formed by processing a portion equivalent to a weight plate portion lower than the above is placed, and the glass plate is a peripheral frame portion in a silicon single crystal layer,
After joining and integrating only to the upper surface of either the central pillar portion formed at the cross-shaped cross portion of the cross-shaped flexible structure portion or the four tip pillar portions, the periphery of the silicon single crystal layer is formed. The boundary between the peripheral frame part equivalent part and the weight plate equivalent part in the glass sheet regulated to the position where the frame part is hung is grooved by a dicing saw, and the groove is formed in the middle of the peripheral frame part of the silicon single crystal layer. A third step of forming a glass layer composed of a peripheral frame portion and a weight plate portion separated therefrom. The silicon single crystal material below the groove of the silicon single crystal layer peripheral frame portion left by the grooving process in the above process,
The silicon single crystal layer peripheral frame is completely penetrated by anisotropic dry etching, and the inner portion of the silicon single crystal layer peripheral frame portion is separated from the outer peripheral lower surface of the weight plate portion of the glass layer. After the glass layer peripheral frame part is vertically continuous and integrated in cross section on the part, the silicon single crystal cover plate joined and supported only by the upper surface of the glass layer peripheral frame part is integrated. Fourth step of crowning. Fifth step of connecting a signal extraction lead wire to a through hole previously formed in the base plate. 5. The method of manufacturing a three-axis acceleration sensor having a package structure according to claim 1, wherein the manufacturing is performed sequentially through the first to fifth steps.