JP2010217189A - Method of manufacturing acceleration sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing an acceleration sensor for forming an opening facing an electrode on an upper substrate while suppressing an increase of the size of the acceleration sensor as a whole. <P>SOLUTION: In the method of manufacturing the acceleration sensor, a second substrate 20 is prepared in the following (A) to (E) processes. (A) A first layer 20D that contains glass as a component and is thinner than a first substrate 1 is prepared. (B) A second layer 20U that contains glass as a component and whose lateral width is narrower than that of the first layer 20D is prepared. (C) An opening 20a is formed at the first layer 20D by sandblasting. (D) After the process (C), the second layer 20U is arranged at a position above a sensor on the top surface of the first layer 20D. (E) After the process (D), the first layer 20D is joined to the second layer 20U by melting joint or positive-electrode joint by heating. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for manufacturing an acceleration sensor, and can be applied to a method for manufacturing an acceleration sensor having an upper substrate for sealing having an opening facing an electrode portion, for example.

  The acceleration sensor is formed by sealing a sensor portion or the like with an upper substrate for sealing and a lower substrate for sealing (hereinafter simply referred to as an upper substrate and a lower substrate). The acceleration sensor also has an electrode portion connected to a sensor portion, a fixed electrode, or the like between the upper substrate and the lower substrate.

  In order to connect the electrode part to an external wire wiring, an opening is conventionally provided in the upper substrate.

  Specifically, an opening facing the electrode portion is formed on the upper substrate, and an electrode wiring connected to the electrode portion from the opening to the upper surface of the upper substrate is formed. And on the upper surface of the upper substrate, the electrode wiring and the wire wiring from the outside are connected by wire bonding. Thereby, the electrode part and the external device are connected via the wire wiring and the electrode wiring, and the potential of the sensor part and the like is taken out from the outside.

  Here, for the purpose of protecting the sensor unit from external pressure, the thickness of the upper substrate and the lower substrate is required to be at least 300 to 400 μm.

  As a method for forming an opening with respect to the upper substrate of the thickness, the following method has been adopted as a conventional technique.

  That is, a non-penetrating recess is formed in the upper substrate to a predetermined thickness by sandblasting, and then the upper substrate and the lower substrate are bonded so as to seal the sensor unit and the like. After that, isotropic etching was performed on the recess to form an opening penetrating the upper substrate.

  For example, when forming an opening in an upper substrate having a thickness of about 400 μm, first, a recess having a depth of about 300 μm is formed by sandblasting. Thereafter, the upper substrate having a thickness of about 100 μm existing at the bottom of the recess is completely removed by an isotropic etching process. During the isotropic etching process, the entire upper surface of the upper substrate is also removed by about 100 μm.

  Thus, an opening penetrating the upper substrate having a thickness of about 300 μm is formed.

  There is also a technique for forming an opening penetrating the upper substrate only by sandblasting processing without using isotropic etching.

  As an acceleration sensor according to the prior art in which an opening is formed in the upper substrate, there is, for example, Patent Document 1.

Japanese Patent Laid-Open No. 10-115635

  When the technology for forming the opening in the upper substrate is adopted by applying the isotropic etching treatment after the sandblasting treatment, or when the technology for forming the opening only by the sandblasting treatment is adopted. Had the following problems.

  That is, since the opening was formed by sandblasting and isotropic etching, the upper substrate was also removed in the lateral direction, and the opening diameter of the opening was increased (in the upper substrate having a thickness of about 300 μm). , About 50 to 200 μm at the bottom of the opening, and about 400 μm at the top of the opening).

  By the way, in order to completely seal the hollow portion, the electrode portion needs to block the bottom surface of the opening portion without any gap. Therefore, the electrode portion needs to be designed to have a size larger than the maximum opening diameter of the expected opening (that is, the size of the electrode portion = the expected maximum opening diameter + the margin size).

  Then, in the case of the above-described prior art, the expected maximum opening diameter is 400 μm, so the size of the electrode portion needs to be larger than 400 μm. Thus, in the case of the above prior art, the expected maximum opening diameter of the opening (specifically, the opening diameter at the top of the opening) was large, so the dimensions of the electrode part were set to be larger. It was.

  As described above, in the prior art, the size of the electrode portion has to be increased, and as a result, the entire size of the acceleration sensor has to be increased.

  Accordingly, an object of the present invention is to provide an acceleration sensor manufacturing method capable of forming an opening facing an electrode portion on an upper substrate while suppressing an increase in the size of the entire acceleration sensor.

  In order to achieve the above object, a method of manufacturing an acceleration sensor according to the present invention includes a first substrate, a first layer disposed to face the first substrate, and a part of the first layer. A second substrate composed of one or a plurality of second layers formed on the upper surface, and a sealed cavity formed and sealed between the first substrate and the second substrate. And the second layer is formed only above the sensor unit, is sandwiched between the first substrate and the second substrate, and surrounds the cavity portion. A frame body, an electrode portion that is disposed in the cavity portion and is connected to one of the sensor portion and the frame body, and the first layer is formed so as to face an upper surface of the electrode portion. An opening, and an electrode wiring formed in the opening and connected to the electrode. The second substrate includes (A) a step of preparing the first layer including glass as a constituent element and being thinner than the first substrate, and (B) glass. And a step of preparing a second layer having a width narrower than that of the first layer, and (C) a step of forming the opening in the first layer by sandblasting, (D) After the step (C), the step of disposing the second layer at a position above the sensor portion on the upper surface of the first layer; and (E) after the step (D). And the step of bonding the first layer and the second layer by fusion bonding by heating or anodic bonding.

  The acceleration sensor manufacturing method according to the present invention includes a first substrate, a first layer disposed opposite to the first substrate, and one or a plurality of upper surfaces formed on a part of the first layer. A second substrate composed of a second layer, and a sensor unit disposed in a sealed cavity formed between the first substrate and the second substrate, The second layer is formed only above the sensor unit, is sandwiched between the first substrate and the second substrate, and includes a frame body that surrounds the cavity portion, and is disposed in the cavity portion. An electrode portion connected to either the sensor portion or the frame, an opening formed in the first layer so as to face an upper surface of the electrode portion, and formed in the opening And a method of manufacturing an acceleration sensor, further comprising electrode wiring connected to the electrode portion. The second substrate includes (A) glass as a constituent element, the step of preparing the first layer having a thickness smaller than that of the first substrate, and (B) glass as a constituent element, A step of preparing a second layer having a narrower width than the first layer, (C) a step of forming the opening in the first layer by sandblasting, and (D) the step (C ), The step of disposing the second layer at a position above the sensor portion on the upper surface of the first layer, and (E) the fusion bonding or anode by heating after the step (D). It is created by joining the first layer and the second layer by joining.

  Therefore, since the opening for electrode sealing is provided by sandblasting in the first layer in the region where the second layer is not formed, the opening having a small maximum opening diameter is provided in the first layer. Can be formed. This is because the thickness of the first layer is relatively thin. The upper part of the sensor unit is covered with a first layer and a second layer. Therefore, since the layer thickness above the sensor portion is increased, the sensor portion and the like can be strongly protected from external pressure.

1 is a cross-sectional view illustrating an overall configuration of an acceleration sensor according to Embodiment 1. FIG. 2 is an enlarged cross-sectional view showing a configuration of an acceleration sensor according to Embodiment 1. FIG. FIG. 6 is a process cross-sectional view for explaining the method of manufacturing the acceleration sensor according to the first embodiment. FIG. 6 is a process cross-sectional view for explaining the method of manufacturing the acceleration sensor according to the first embodiment. FIG. 6 is a process cross-sectional view for explaining the method of manufacturing the acceleration sensor according to the first embodiment. FIG. 6 is a process cross-sectional view for explaining the method of manufacturing the acceleration sensor according to the first embodiment. FIG. 6 is a process cross-sectional view for explaining the method of manufacturing the acceleration sensor according to the first embodiment. FIG. 6 is a process cross-sectional view for explaining the method of manufacturing the acceleration sensor according to the first embodiment. FIG. 6 is a process cross-sectional view for explaining the method of manufacturing the acceleration sensor according to the first embodiment. FIG. 6 is a process cross-sectional view for explaining the method of manufacturing the acceleration sensor according to the first embodiment. FIG. 6 is a process cross-sectional view for explaining the method of manufacturing the acceleration sensor according to the first embodiment. FIG. 4 is a cross-sectional view for explaining a problem of the acceleration sensor according to the first embodiment. FIG. 6 is an enlarged cross-sectional view illustrating a configuration of an acceleration sensor according to a second embodiment. FIG. 6 is an enlarged cross-sectional view illustrating a configuration of an acceleration sensor according to a third embodiment.

  Hereinafter, the present invention will be specifically described with reference to the drawings showing embodiments thereof.

<Embodiment 1>
FIG. 1 is a sectional view showing the configuration of the acceleration sensor according to the first embodiment. FIG. 2 is an enlarged cross-sectional view showing a configuration in the vicinity of the electrode portion 7 and the opening 2a of the acceleration sensor shown in FIG. Here, the movable mass body 4 and the fixed electrode 5 are collectively referred to as a sensor unit.

  The actual acceleration sensor has a more complicated configuration than the shapes shown in FIGS. 1 and 2 in the shape of the movable mass body 4 and the fixed electrode 5. However, in FIGS. 1 and 2, the shapes of the movable mass body and the fixed electrode 5 are simplified for simplification.

  As shown in FIGS. 1 and 2, a sealing multi-layer second substrate (hereinafter simply referred to as a multi-layer second substrate) 2 opposed to a sealing first substrate (hereinafter simply referred to as a first substrate) 1. Is arranged.

  Here, the 1st board | substrate 1 is comprised, for example with glass, The thickness is about 400 micrometers.

  The multilayer second substrate 2 is composed of a plurality of layers. That is, the multilayer second substrate 2 has a laminated structure in which a glass layer, a low melting point glass layer (or silicon layer), and a glass layer are laminated in this order from the lower layer. Here, the thickness of each layer constituting the multilayer second substrate 2 is about 100 μm.

  A sealed cavity 3 is formed between the first substrate 1 and the multilayer second substrate 2 facing each other. A movable mass body 4 is disposed in the cavity 3. Here, the movable mass body 4 is configured to be freely movable in the cavity 3.

  Further, a fixed electrode 5 is disposed in the vicinity of the movable mass body 4 in the cavity 3 with a predetermined space therebetween.

  As described above, the movable mass body 4 and the fixed electrode 5 constitute a sensor unit.

  By observing a change in electrostatic force generated between the movable mass body 4 and the fixed electrode 5, the acceleration applied to the acceleration sensor can be measured.

  A frame 6 is formed so as to be sandwiched between the first substrate 1 and the multilayer second substrate 2. Here, the frame 6 is formed so as to surround the cavity 3.

  Further, an electrode portion 7 is disposed in the cavity portion 3. The electrode part 7 is connected to either the sensor part (the movable mass body 4, the fixed electrode 5) or the frame body 6.

  For example, if the electrode part 7 is an electrode for extracting the potential of the movable mass body 4 (fixed electrode part 5), the electrode part 7 is connected to the movable mass body 4 (fixed electrode 5). For example, if the electrode part 7 is an electrode for setting the potential of the frame body 6 to the ground potential, the electrode part 7 is connected to the frame body 6.

  The multilayer second substrate 2 is formed with an opening 2a for extracting an electrode. The opening 2a is formed from the upper surface to the lower surface of the multilayer second substrate 2 (that is, the opening 2a is formed in the multilayer second substrate 2 so as to penetrate from the upper layer to the lower layer). . Further, the electrode part 7 is exposed from the bottom surface of the opening part 2a (that is, the opening part 2a is formed so as to face the upper surface of the electrode part 7). The opening diameter of the opening 2a is about 50 to 200 μm at the bottom and about 200 to 300 μm at the top.

  An electrode wiring 8 is formed inside the opening 2a. The electrode wiring 8 is connected to the electrode portion 7 and is formed from the inside of the opening 2 a to a part of the upper surface of the multilayer second substrate 2. The film thickness of the electrode wiring 8 is about 3 μm.

  A wire wiring 9 is bonded to the electrode wiring 8 disposed on the upper surface of the multilayer second substrate 2. Accordingly, the extraction of the potential, the setting of the ground potential, and the like between the external device and the electrode unit 7 are performed through the wire wiring 9 and the electrode wiring 8.

  Next, a method for manufacturing the acceleration sensor according to the present embodiment will be described.

  First, as shown in FIG. 3, a glass layer 2A, a low-melting glass layer (or silicon layer) 2B, and a glass layer 2C constituting the multilayer second substrate 2 are prepared.

  Then, as shown in FIG. 3, openings 2aa, 2ab, 2ac, which are through-holes, are formed on the respective layers 2A, 2B, 2C separately and independently. The openings 2aa to 2ac are formed by, for example, sandblasting.

  Here, the openings 2aa to 2ac are formed by the sand blasting process for each of the layers 2A, 2B, and 2C having a layer thickness of about 100 μm. Moreover, the cross-sectional shape of the openings 2aa to 2ac formed by the sandblast opening process is a mortar shape (shown as a rectangular shape in the drawing).

  Therefore, if the opening diameter at the bottom of the openings 2aa to 2ac is about 50 to 200 μm, the opening diameter at the top of the openings 2aa to 2ac is about 200 to 300 μm.

  In each of the layers 2A to 2C, the opening diameters and the cross-sectional shapes of the openings 2aa to 2ac are almost the same.

  Next, as shown in FIG. 4, the layers 2 </ b> A to 2 </ b> C are overlapped while adjusting the position so that the centers of the opening diameters of the openings 2 aa to 2 ac are aligned. And after the said superposition | superposition, the joining process of each layer 2A-2C is given.

  Here, when the low-melting glass layer 2B is used as the intermediate layer, the layers 2A to 2C are welded and joined by heat treatment. When the silicon layer 2B is used as the intermediate layer, the layers 2A to 2C are bonded by anodic bonding. Thereby, the multilayer 2nd board | substrate 2 provided with the opening part 2a of a small opening diameter is formed.

  On the other hand, a bulk silicon 10 having a thickness of about 625 μm is prepared. Then, by performing an anisotropic etching process, a part of the upper surface of the silicon 10 (above the movable mass 4 to be formed later) is removed by about 10 μm. The state of the silicon 10 after the anisotropic etching process is shown in FIG.

  Next, the upper surface of the silicon 10 shown in FIG. 5 and the lower surface of the multilayer second substrate 2 shown in FIG. 4 are joined by anodic bonding. The state after the anodic bonding is shown in FIG.

  Next, by polishing the lower surface of the silicon 10 after the anodic bonding, the thickness of the silicon 10 is reduced to about 57 μm as shown in FIG.

  Next, an anisotropic etching process is performed on the lower surface of the silicon 10 after the polishing process. Thereby, as shown in FIG. 8, the sensor part (the movable mass body 4 and the fixed electrode 5), the electrode part 7, the frame body 6 and the like are patterned for the silicon 10.

  On the other hand, a first substrate 1 made of glass or the like and having a thickness of about 400 μm is prepared. Then, a part of the upper surface of the first substrate 1 is removed by anisotropic etching. The state after the removal is shown in FIG.

  Next, as shown in FIG. 10, the lower surface of the silicon 10 shown in FIG. 8 and the upper surface of the first substrate 1 shown in FIG. 9 are joined by anodic bonding.

  As shown in FIG. 10, a cavity 3 is formed between the multilayer second substrate 2 and the first substrate 1, and in the cavity 3, a sensor unit (movable mass body 4, fixed electrode 5), An electrode portion 7 is provided. A frame 6 is formed so as to surround the cavity 3, and the frame 6 is sandwiched between the multilayer second substrate 2 and the first substrate 1 at the outer periphery. The movable mass body 4 is disposed so as to be freely movable in the cavity 3.

  Next, an aluminum deposition process is performed on the structure shown in FIG. 10 from above. By the vapor deposition process, as shown in FIG. 11, an aluminum electrode wiring 8 having a thickness of about 3 μm is disposed. The electrode wiring 8 is formed from the opening 2 a to a part of the upper surface of the multilayer second substrate 2. The electrode wiring 8 is connected to the electrode portion 7 at the bottom of the opening 2a. Furthermore, on the upper surface of the multilayer second substrate 2, the electrode wiring 8 is formed in a substantially rectangular shape in plan view.

  Thereafter, the wire wiring 9 is connected to the electrode wiring 8 disposed on the upper surface of the multilayer second substrate 2. The connection can be performed by a wire bonding process using ultrasonic waves.

  The acceleration sensor configured as shown in FIGS. 1 and 2 is completed through the above steps.

  In the acceleration sensor according to the present embodiment, as described above, the multilayer second substrate 2 is composed of a plurality of layers 2A to 2C. Accordingly, the thickness of each of the layers 2A to 2C is thinner than the entire thickness of the multilayer second substrate 2, and thus has the following effects.

  When the opening 2a is formed by sandblast processing, the cross-sectional shape of the opening 2a is a bowl shape. That is, the opening diameter of the opening increases from the bottom to the top of the opening. Therefore, when the opening 2a is formed on the thick second substrate by the sandblasting process, the opening diameter of the upper portion of the opening 2a becomes very large.

  For example, it is assumed that a sandblasting process is performed on the second substrate having a thickness of about 300 μm to form the opening 2a. In this case, if the opening diameter at the bottom of the opening 2a is about 50 to 200 μm, the opening diameter at the top of the opening is about 400 μm or more.

  However, when the acceleration sensor according to the present embodiment is employed, the openings 2aa to 2ac can be formed independently for each of the thin layers 2A to 2C. Therefore, the magnitude | size of the opening diameter in the upper part of each opening part 2aa-2ac can be suppressed, As a result, the magnitude | size of the diameter in the upper part of the opening part 2a of the multilayer 2nd board | substrate 2 can be made smaller.

  For example, it is assumed that sandblasting is performed on the layers 2A to 2C having a thickness of about 100 μm to form the openings 2aa to 2ac. In this case, if the size of the opening diameter at the bottom of the openings 2aa to 2ac is about 50 to 200 μm, the size of the opening diameter at the top of the openings 2aa to 2ac is about 200 to 300 μm.

  Accordingly, the opening diameter of the opening 2a of the multilayer second substrate 2 is also about 200 to 300 μm at the top (the diameter is about 50 to 200 μm at the bottom of the opening 2a).

  As described above, the electrode part 7 needs to be designed to have a size larger than the expected maximum diameter of the opening 2a. And in the case of the said prior art, if the opening diameter in the bottom part of an opening part shall be about 50-200 micrometers, the dimension of an electrode part needs to be larger than 400 micrometers of the estimated maximum opening diameter.

  However, when the acceleration sensor according to the present embodiment is applied, if the opening diameter at the bottom of the opening 2a is about 50 to 200 μm, the size of the electrode 3 is the expected maximum opening diameter of the opening 2a. What is necessary is just to be larger than 200 micrometers-300 micrometers.

  As can be seen from comparison between the two, the acceleration sensor according to the present embodiment can set the size of the electrode portion 3 to be smaller.

  Thus, since the dimension of the electrode part 7 can be made small by employ | adopting the acceleration sensor which concerns on this Embodiment, as a result, the magnitude | size of the whole acceleration sensor can be made small. That is, by adopting the acceleration sensor according to the present embodiment, it is possible to form the opening 2a facing the electrode portion 7 in the second substrate 2 while suppressing an increase in the size of the entire acceleration sensor.

  In addition, the material, dimension, etc. of each member are examples, and it is not necessary to restrict to this. In particular, the number of layers of each of the layers 2A to 2C constituting the multilayer second substrate 2 is not necessarily limited to three as described above. For example, the number of layers may be two or four or more. Note that the thickness of each layer can be reduced as the number of layers of the multilayer second substrate 2 is increased.

<Embodiment 2>
In the first embodiment, the opening diameters and the cross-sectional shapes of the openings 2aa to 2ac formed in the layers 2A to 2C are all substantially the same. However, the first embodiment having such a configuration has the following problems.

  That is, in order to construct the multilayer second substrate 2, the layers 2 </ b> A to 2 </ b> C need to be overlaid (see FIG. 4). The center of the opening diameter of the opening may be shifted in the horizontal direction. An example in the case where such a deviation occurs is shown in FIG. In FIG. 12, the center of the opening diameter of the opening of the layer 2B is shifted leftward with respect to the center of the opening diameter of the opening of the layer 2C.

  When the deviation occurs, for example, in a circled portion (FIG. 12), the layer 2B becomes a wrinkle in the step of arranging the electrode wiring 8 (vapor deposition process) with respect to the layer 2C. Therefore, the electrode wiring 8 is not normally disposed in the circled portion, and disconnection occurs.

  Therefore, in the acceleration sensor according to the present embodiment, the opening diameter of the opening formed in the upper layer is made larger than the opening diameter of the opening formed in the lower layer. FIG. 13 shows an acceleration sensor having an opening having such a configuration. Here, FIG. 13 is an enlarged cross-sectional view showing a configuration in the vicinity of the electrode portion 7 and the opening 2a of the acceleration sensor.

  As shown in FIG. 13, in the acceleration sensor according to the present embodiment, the cross-sectional shape of the opening 2a is widened in a staircase shape from the bottom to the top.

  That is, the size of the opening diameter at the bottom of the opening 2ab of the intermediate layer 2B is larger than the size of the opening at the top of the opening 2ac of the lowermost layer 2C. Further, the size of the opening diameter at the bottom of the opening 2aa of the uppermost layer 2B is larger than the size of the opening at the top of the opening 2ab of the intermediate layer 2B.

  In addition, when each opening part 2aa-2ac is formed with respect to each layer 2A-2C by sandblasting process, the cross-sectional shape of each opening part 2aa-2ac becomes a bowl shape. However, in FIG. 13, for simplification, the cross-sectional shapes of the openings 2aa to 2ac are substantially rectangular.

  Since the configuration other than the cross-sectional shape of the opening 2a is the same as that of the first embodiment, the description thereof is omitted here.

  In the acceleration sensor according to the present embodiment, the opening 2a having the stepped cross-sectional shape is formed. Therefore, even when the upper layer is slightly shifted in the horizontal direction with respect to the lower layer during the overlay processing for the configuration of the multilayer second substrate 2, the upper layer is disposed in the step of arranging the electrode wiring 8 (evaporation) with respect to the lower layer. It is possible to prevent wrinkles during processing.

  As described above, since some misalignment is allowed, assembly (superposition) of the multilayer second substrate 2 is facilitated. Further, even if some layer misalignment occurs, disconnection of the electrode wiring 8 can be prevented.

<Embodiment 3>
FIG. 14 shows the configuration of the acceleration sensor according to the present embodiment. Here, FIG. 14 is an enlarged cross-sectional view showing a configuration in the vicinity of the electrode portion 7 and the opening 20a of the acceleration sensor.

  As shown in FIG. 14, the acceleration sensor according to the present embodiment includes a first substrate 1 and a second substrate 20 disposed to face the first substrate 1.

  The second substrate 20 is composed of a first layer 20D and a second layer 20U. Here, the first layer 20 </ b> D is disposed to face the first substrate 1. The second layer 20U is formed on a predetermined upper surface of the first layer 20, and is composed of a plurality of layers.

  The layer thickness of the first layer 20D is about 100 μm, and the entire layer thickness of the second layer 20U is about 200 μm (thus, in the portion where the second layer 20U is formed, the second substrate 20 The total layer thickness is about 300 μm). The configuration of the first substrate 1 is the same as that of the first embodiment.

  Further, for example, a glass layer can be adopted as the first layer 20D. The second layer 20U is composed of, for example, a glass layer (upper layer) 20U1 / a low melting point glass layer (silicon layer) (lower layer) 20U2.

  Further, in the first layer 20D and the second layer 20U, the end on the opening 20a side has a stepped shape extending from the bottom to the top. That is, on the opening 20a side, the end of the layer 20U2 protrudes from the end of the layer 20U1, and the end of the first layer 20D protrudes from the end of the layer 20U2.

  Similar to the first embodiment, the movable mass body 4 is disposed in the sealed cavity 3 formed between the first substrate 1 and the second substrate 20 facing each other. In addition, a fixed electrode 5 is disposed in the cavity 3 in the vicinity of the movable mass body 4. A frame body 6 is provided on the outer periphery of the first substrate 1 and the second substrate 20 so as to be sandwiched between the substrates 1 and 20. Here, the frame body 6 surrounds the cavity 3. Furthermore, an electrode part 7 is disposed in the cavity part 3, and the electrode part 7 is connected to either the sensor part (the movable mass body 4, the fixed electrode 5) or the frame body 6.

  In the acceleration sensor according to the present embodiment, only the first layer 20D is formed above the frame 6 as shown in FIG. Specifically, only the first layer 20 </ b> D is formed in a portion from the upper surface of the frame body 6 to a part of the upper surface of the electrode portion 7 through the narrow cavity portion 3.

  Further, as shown in FIG. 14, a second layer 20U is stacked on the first layer 20D above the sensor unit. Specifically, the second layer 20U is stacked on the first layer 20D in a part of the upper surface of the electrode unit 7 while being stacked above the sensor unit.

  That is, only the first layer 20 </ b> D is disposed in a portion where the mechanical strength in the cavity 3 is strong against the external pressure from the vertical direction of the drawing. On the other hand, the second layer 20U is also disposed in a portion where the mechanical strength in the cavity 3 with respect to external pressure from the vertical direction of the drawing is weak. For example, as can be seen from FIG. 14, the arrangement portion of the frame body 6 has a high mechanical strength against external pressure from the vertical direction of the drawing. In addition, the movable mass body 4 and the fixed electrode 5 in which the volume of the cavity 3 is large have a low mechanical strength against external pressure from the vertical direction of the drawing.

  In the first layer 20D, an opening 20a is formed so as to face the upper surface of the electrode portion 7.

  The electrode wiring 8 is formed in the opening 20 a and reaches part of the upper surface of the second substrate 20. Here, the electrode wiring 8 has a pad portion connectable to the wire wiring 9 from the outside on the upper surface of the first layer 20D. The electrode wiring 8 is connected to the electrode portion 7.

  The second substrate 20 included in the acceleration sensor according to the present embodiment can be formed as follows, for example.

  First, a first layer 20D such as glass is prepared. Also, a low-melting glass layer (or silicon layer) 20U2 having a narrower width than the first layer 20D and a glass layer 20U1 having a narrower width than the low-melting glass layer (or silicon layer) 20U2 are prepared.

  Next, the opening 20a is formed at a predetermined position of the first layer 20D by, for example, sandblasting. Thereafter, a low melting point glass layer (or silicon layer) 20U2 is disposed (overlapped) at a predetermined position on the upper surface of the first layer 20D, and the glass layer 20U1 is disposed at a predetermined position on the upper surface of the low melting point glass layer (silicon layer) 20U2. Arrange (superimpose).

  Specifically, the second layer 20U is disposed on the first layer 20D in the region where the movable mass body 4 and the fixed electrode 5 are disposed. Further, the first layer 20D and the second layer 20U are arranged so that the end portions of the layers 20D, 20U1, and 20U2 on the side where the opening 20a is formed spread in a stepped manner from the bottom to the top in a cross-sectional view. Arrange.

  Then, after the superposition process, the layers 20D and 20U are subjected to bonding processing (for example, fusion bonding by heating or anodic bonding).

  As described above, the second substrate 20 according to the present embodiment having the opening 20a can be formed.

  The acceleration sensor according to the present embodiment includes the second substrate 20 having the above configuration. Therefore, if the sand blasting process is performed on the first layer 20D having a small layer thickness, the opening 20a having a small opening diameter can be formed as in the first embodiment. (Furthermore, since the size of the electrode portion 7 can be reduced, the size of the entire sensor can also be reduced).

  Further, in the acceleration sensor according to the present embodiment, the second layer 20U is formed only in a portion where the mechanical strength in the cavity 3 with respect to the external pressure from the vertical direction of the drawing is weak. Therefore, the manufacturing cost can be reduced and the weight of the entire acceleration sensor can be reduced as compared with the case where all of the second substrate 20 has a multilayer structure.

  In the acceleration sensor according to the present embodiment, the electrode wiring 8 is formed from the opening 20a to the upper surface portion of the first layer 20D, and the pad portion is formed on the upper surface portion of the first layer 20D. have.

  Therefore, when the second layer 20U is overlaid on the first layer 20D, unless the second layer 20U is extremely displaced in the horizontal direction, the connection portion of the electrode portion 7 is placed on the upper surface of the first layer 20D. In the route to reach, there is no occurrence of a part that becomes a wrinkle when the electrode wiring 8 is formed (deposition process). Therefore, the electrode wiring 8 can be formed without being disconnected.

  In the above description, in the first layer 20D and the second layer 20U, the end on the opening 20a side has been described as having a stepped shape extending from the bottom to the top. However, the case where it does not have the said staircase shape may be sufficient.

  Moreover, the material, dimension, etc. of each member are examples, and it is not necessary to limit to this. In particular, the number of layers 20U1 and 20U2 constituting the second layer 20U does not have to be limited to two as described above. For example, the number of layers may be one or three or more. Note that the thickness of each layer can be reduced as the number of layers of the multilayer second substrate 2 is increased.

  DESCRIPTION OF SYMBOLS 1 1st board | substrate, 2 multilayer 2nd board | substrate, 3 cavity part, 4 sensor part, 5 fixed electrode, 6 frame, 7 electrode part, 8 electrode wiring, 9 wire wiring, 20 2nd board | substrate, 20D 1st layer , 20U second layer, 2a, 20a opening.

Claims (1)

A second layer comprising a first substrate, a first layer disposed opposite to the first substrate, and one or more second layers formed on a part of the first layer; And a sensor unit disposed in a sealed cavity formed between the first substrate and the second substrate, wherein the second layer is formed of the sensor unit. Formed only above, sandwiched between the first substrate and the second substrate, surrounding the cavity, and disposed in the cavity, the sensor unit and the frame An electrode portion connected to one of the body, an opening formed in the first layer so as to face an upper surface of the electrode portion, and an electrode formed in the opening and connected to the electrode portion A method of manufacturing an acceleration sensor further comprising:
The second substrate is
(A) including glass as a constituent element and preparing the first layer having a thickness smaller than that of the first substrate;
(B) a step of preparing a second layer containing glass as a component and having a narrower width than the first layer;
(C) forming the opening in the first layer by sandblasting;
(D) After the step (C), disposing the second layer at a position above the sensor portion on the upper surface of the first layer;
(E) After the step (D), it is created by a step of bonding the first layer and the second layer by fusion bonding or anodic bonding by heating.
A method for manufacturing an acceleration sensor.

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