JP5067019B2 - Manufacturing method of mechanical quantity detection sensor - Google Patents

Description

  The present invention relates to a method of manufacturing a mechanical quantity detection sensor that detects a mechanical quantity such as acceleration and angular velocity.

In recent years, attention has been focused on MEMS (Micro Electro Mechanical Systems), which are devices that integrate various functions such as mechanical, electronic, optical, and chemical using semiconductor microfabrication technology and the like. These are arranged in a plurality of chip regions in a semiconductor wafer, and a large number of devices can be formed in the wafer. Examples of devices that have been put to practical use include mechanical quantity detection sensors such as an acceleration sensor and an angular velocity sensor. A mechanical quantity sensor for detecting acceleration, which is formed by joining a semiconductor transducer structure to a glass substrate. A technique is disclosed (see Patent Document 1).
JP 2003-329702 A

  As an example of the operating principle of the above-described mechanical quantity detection sensor, a mechanical quantity is detected by measuring a change in an electric signal accompanying a vibration displacement of a weight part (weight part) provided in each element. The displaced weight portion is connected to a frame portion (fixed portion) fixed by at least one beam portion (connecting portion) having flexibility. The weight part in the sensor is supported by the beam part and exists in a hollow state. Generally, a flexible beam portion is configured as a self-supporting thin film (membrane) and is physically fragile.

The above-described mechanical quantity detection sensor is manufactured using a known semiconductor microfabrication technique. In general, a silicon substrate or an SOI (Silicon On Insulator) substrate having a three-layer structure of silicon / silicon dioxide / silicon is used, and a desired process is performed on each layer to form a membrane (beam portion). A plurality of membrane structures having these membranes are arranged in a chip area in the wafer.
Here, the membrane is a free-standing thin film composed of at least one layer made of a metal or a semiconductor material, and refers to a functional part having a thickness of, for example, several nanometers to several tens of micrometers. The membrane is formed, for example, by etching the above-described semiconductor substrate. A dry etching method is used as such an etching method. The detection sensitivity of the mechanical quantity detection sensor depends on the flexibility of the beam portion, and a design attempt is made such as reducing the thickness of the beam portion in order to manufacture a highly sensitive product.

However, the physical strength of the membrane is very fragile. For example, the membrane (beam portion) is damaged by pressure fluctuation or impact during the process, and falls off the sensor frame. In the dry etching method, the substrate is cooled by supplying a gas such as helium from the back side of the substrate during the process. However, there is a problem that the cooling efficiency of the substrate is lowered due to the membrane breakage and the process performance is lowered. It turns out that there is.
In view of the above, it is an object of the present invention to provide a method for manufacturing a mechanical quantity detection sensor that can suppress breakage of a membrane produced in a mechanical quantity detection sensor element and can reduce deterioration in process performance. And

The manufacturing method of the mechanical quantity detection sensor according to the present invention uses a semiconductor substrate in which a first layer made of a semiconductor material, a second layer made of an insulating material, and a third layer made of a semiconductor material are sequentially laminated. A fixing portion having an opening in the first layer, a displacement portion disposed in the opening and displaced with respect to the fixing portion, and a connection portion connecting the fixing portion and the displacement portion. A first structure forming step of forming a first structure, a protective layer disposing step of providing a protective layer made of a water-soluble polymer material or an organic solvent-soluble polymer material on the first structure side, A semiconductor substrate is integrally formed with the protective layer, and is etched in the thickness direction of the semiconductor substrate to be bonded to the displacement portion with the third layer. A second structure forming a second structure including a frame portion to be joined Including a structure forming step and a protective layer removing step of removing the protective layer after the second structure forming step, and supporting the semiconductor substrate and forming a rigid plate in the protective layer disposing step A substrate is disposed so that the protective layer is sandwiched between the support substrate and the semiconductor substrate, the protective layer is provided on at least one of the semiconductor substrate or the support substrate, and the semiconductor substrate is interposed via the protective layer. And further comprising a step of arranging the support substrate and the support substrate so that the support substrate has a groove portion on a surface facing the semiconductor substrate, and a cavity portion is formed between the groove portion and the protective layer, In the protective layer removing step, a separation liquid for removing the protective layer enters the cavity.
The manufacturing method of the mechanical quantity detection sensor according to the present invention includes a semiconductor substrate in which a first layer made of a semiconductor material, a second layer made of an insulating material, and a third layer made of a semiconductor material are sequentially laminated. A fixing portion having an opening in the first layer; a displacement portion disposed in the opening and displaced with respect to the fixing portion; and a connection portion connecting the fixing portion and the displacement portion. A first structure forming step of forming a first structure including: a protective layer disposing step of providing a protective layer made of a water-soluble polymer material or an organic solvent-soluble polymer material on the first structure side; The semiconductor substrate is integrally formed with the protective layer, and is etched in the thickness direction so as to be joined to the third layer by the displacement portion. The weight portion is disposed so as to surround the weight portion and is fixed. Forming a second structure including a frame portion joined to the portion A second structural body forming step; and a protective layer removing step of removing the protective layer after the second structural body forming step. In the protective layer disposing step, the semiconductor substrate is supported and a rigid plate A support substrate comprising the support substrate and the semiconductor substrate so as to sandwich the protective layer, the protective layer being provided on at least one of the semiconductor substrate or the support substrate, and the protective layer interposed therebetween. A step of arranging the semiconductor substrate and the support substrate so as to be joined, the support substrate having a through hole, and a separation liquid for removing the protective layer in the protective layer removing step in the through hole; It is characterized by intrusion.

  An object of this invention is to provide the manufacturing method of the mechanical quantity detection sensor which can suppress the failure | damage of the membrane in a mechanical quantity detection sensor element, and can reduce the fall of process performance.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
<Example 1>
The present invention relates to a method for manufacturing a mechanical quantity detection sensor. First, the structure of the acceleration sensor manufactured by the method of the present invention and the manufacturing method thereof will be described. Further, as another aspect of the mechanical quantity detection sensor, the structure of the angular velocity sensor and the manufacturing method thereof will be described later.
1 to 3 are views showing an acceleration sensor according to an embodiment of the present invention. FIG. 1 is a perspective view of the acceleration sensor, FIG. 2 is an exploded perspective view of the acceleration sensor, and FIG. 3 is a top view of the acceleration sensor (a). ) And a cross-sectional view (b) taken along line AA in the top view thereof (however, the wiring portion and the like are not shown for the sake of easy viewing). As shown in FIG. 3A, the top view of the acceleration sensor 100 is substantially square, and has a size of, for example, 1 mm square.
The acceleration sensor is composed of a semiconductor substrate in which a first layer made of a semiconductor material, a second layer made of an insulating material, and a third layer made of a semiconductor material are sequentially stacked. The semiconductor substrate is, for example, an SOI (Silicon On Insulator) substrate. In this case, the first layer is an active layer 3 made of silicon, the second layer is a BOX (buried oxide film) layer 4 made of silicon dioxide, and a third layer. These layers are the support layers 5 made of silicon, and have thicknesses of 2 μm to 10 μm, 0.5 to 3 μm, and 300 to 800 μm, respectively. The lower surface (the support layer 5 side) of the SOI substrate 1 and the upper surface of the glass substrate 2 are joined and configured integrally.

  As the glass substrate 2, for example, so-called Pyrex (registered trademark) glass containing movable ions such as Na ions is used. As will be described later, the SOI substrate 1 and the glass substrate 2 are bonded by anodic bonding. The glass substrate 2 functions as a stopper function for preventing excessive displacement of the weight part 5a (described later) and a pedestal of the sensor, and the material is not limited to glass as long as it fulfills the above functions. . As such a material, for example, silicon, resin, metal, or the like can be used.

  The active layer 3 includes a fixed portion 3c having four openings 3d, a rectangular flat plate-like displacement portion 3a disposed in the opening 3d and displaced with respect to the fixed portion 3c, and a fixed portion 3c. There are four connecting portions 3b that connect the displacement portion 3a. A piezoresistor R is formed in the connecting portion 3b.

  The supporting layer 5 is joined to the vertical portion approximately clover-like weight portion 5a joined to the displacement portion 3a via the joining portion 4a provided on the BOX layer 4, and to the fixing portion 3c so as to surround the weight portion 5a. A frame portion 5b is disposed.

  Three ends of the piezoresistors Rx1 to Rx4, Ry1 to Ry4, and Rz1 to Rz4 are connected to the end of the connecting portion 3b connected to the displacement portion 3a and the end of the connecting portion on the connecting portion. Arranged in the direction. These three sets of twelve piezoresistors R are formed by impurity diffusion wiring, and are connected to a pattern by the impurity diffusion wiring. Further, an opening is formed at a predetermined position on the pattern and is connected to the aluminum wiring. (Patterns and the like are not shown). The pattern or the aluminum wiring forms a Wheatstone bridge circuit, and details of the circuit are based on Japanese Patent Application Laid-Open No. 2006-258528 by the applicant of the present application, and the description thereof is omitted in this specification.

(Acceleration sensor manufacturing method)
Next, a manufacturing process of the acceleration sensor 100 will be described based on the above-described structure and the like.
FIG. 4 is a flowchart showing an example of a manufacturing procedure of the acceleration sensor according to the embodiment of the invention. FIG. 5 is a sectional view showing the state of the acceleration sensor in the manufacturing procedure of FIG.

(1) Preparation of SOI substrate (step S11 and FIG. 5 (a))
As shown in FIG. 5A, an SOI substrate 1 including a support layer 5, a BOX layer 4, and an active layer 3 is prepared. The SOI substrate is manufactured by a SIMOX (Separated by Implanted Oxygen) method or a bonding method.

(2) First structure formation (step S12 and FIGS. 5B to 5D)
The first structure formation is performed as follows.
a. Formation of Diffusion Layer The diffusion layer is formed by stacking SiN (silicon nitride film) on the active layer 3 by, for example, CVD (Chemical Vapor Deposition) method, and opening the diffusion layer pattern by RIE (Reactive Ion Etching) using the resist as a mask (see FIG. (Not shown). For example, an impurity layer containing B (boron) is applied to the pattern opening by spin coating, and then heat-treated at about 1000 ° C. to diffuse the impurities contained in the impurity layer into the active layer, thereby forming the diffusion layer 11. To do. The unnecessary diffusion mask (SiN) is removed by etching with hot phosphoric acid. (Fig. 5 (b))

b. Formation of Wiring The wiring layer is formed by forming the insulating layer 12 on the active layer 3. The insulating layer 12 can be formed, for example, by thermally oxidizing the surface of the active layer 3 to form a silicon dioxide layer. A contact hole (opening) 13 is formed in the insulating layer 12 by, for example, RIE using a resist as a mask.
Next, an Al layer containing Al or Nd is formed on the active layer 3 by, for example, sputtering or vapor deposition. When an Al—Nd alloy is used for the wiring or the like, generation of hillocks (spherical protrusions) is suppressed in the subsequent heating step, which is preferable. The metal layer formed by this deposition is subjected to, for example, wet etching using a resist as a mask, thereby forming the wiring 15 on the active layer 3 and the interlayer connector 14 in the contact hole 13.

c. Next, the SiN layer is deposited by CVD, the protective layer 16 is formed on the active layer 3, the SOI substrate 1 is heat-treated at about 380 ° C. or 400 ° C., and the diffusion layer 11 and the wiring 15 are formed. Make ohmic contact. Thereafter, the protective layer 16 is etched by, for example, RIE using a resist as a mask to form a pad opening 17 in the protective layer 16 (FIG. 5C).

d. Etching of Active Layer By etching the active layer 3, an opening 3d is formed, and a displacement portion 3a, a connecting portion 3b, and a fixing portion 3c are formed. For example, an etching method that has erosion with respect to the active layer 3 and does not have erosion with respect to the BOX layer 4 (or is lower than the erosion of the active layer 3) is used as such etching. Is possible. Thus, etching is performed in the thickness direction until the upper surface of the BOX layer 4 is exposed to the opening 3d, thereby forming a first structure (FIG. 5C).

e. Formation of Conducting Portion 19 An opening corresponding to the through hole 18 is formed in the insulating layer 12 by RIE using a resist as a mask. Thereafter, the active layer 3 whose upper surface is exposed from this opening is etched in the thickness direction until the upper surface of the BOX layer 4 is exposed, thereby forming a through hole 18.
In the through hole 18, for example, Al is deposited by vapor deposition, sputtering, or the like to form a conduction portion 19 (FIG. 5D).

(3) Formation of protective layer (step S12 and FIG. 5 (e))
A protective layer is formed on the active layer 3 side.
The protective layer 6 can be formed, for example, by applying a liquid obtained by dissolving a water-soluble polymer material in water. For example, polyvinyl alcohol (PVA) can be used as the water-soluble polymer material. Application | coating of polyvinyl alcohol is performed by the known application | coating method, for example, is apply | coated with the film thickness of 3-5 micrometers.
Polyvinyl alcohol has high resistance to plasma etching and does not cause foaming or the like during etching, so that it does not cause process abnormality. In this embodiment, polyvinyl alcohol is used. However, the present invention is not limited to this, and a water-soluble polymer material that can be easily peeled off with a water-soluble liquid such as water or alcohol can be used. In addition to the water-soluble polymer material, an organic solvent-soluble polymer can be used.
As another embodiment of the protective layer 6, a sheet having an adhesive surface that can be peeled off by energy irradiation (heating or ultraviolet irradiation) can be used as the protective layer. As such a sheet, for example, UV (ultraviolet) release sheet (Selfa BG (heat-resistant type) manufactured by Sekisui Chemical Co., Ltd.) or thermal release sheet (Riva Alpha (model number: 319Y-4H) manufactured by Nitto Denko Corporation) Can be used.
The protective layer 6 is formed on the upper surface of the active layer 3 by any of the materials and methods described above (FIG. 5E).
Moreover, in the structure provided with a support substrate as will be described later, the protective layer 6 can also be provided by the above materials and methods when provided on the support substrate side.

(4) Processing of support layer (step S13 and FIG. 5 (f))
The processing of the support layer 5 is made in two stages.
1) Production of gap A resist layer having a pattern corresponding to the frame portion 5b is formed on the lower surface of the support layer 5, and an exposed portion not covered with the resist layer is eroded vertically upward. As a result, a gap (for example, 5 to 10 μm) is formed on the lower surface of the support layer 5.

2) Formation of weight part 5a and frame part 5b On the lower surface of the support layer 5, a resist layer having a pattern corresponding to the weight part 5a and the frame part 5b is formed, and an exposed part that is not covered with the resist layer is formed. Etching is performed by an etching method described later until the lower surface of the silicon oxide film 4 is exposed. Thereby, the weight part 5a and the frame part 5b (second structure) are formed (FIG. 5F).

  An example of the etching method described above is DRIE (Deep Reactive Ion Etching). In this method, an etching step of digging while eroding the material layer in the thickness direction and a deposition step of forming a polymer wall on the side wall of the carved hole are alternately repeated. Since the side walls of the holes that have been dug are protected by the formation of polymer walls in sequence, it is possible to cause erosion only in the thickness direction, and an ion / radical supply gas such as SF6 is used as the etching gas. C4F8 or the like can be used as the deposition gas.

The inductively coupled plasma etching apparatus will be described with reference to FIG. The etching apparatus 60 includes a chamber 61, an electromagnetic coil 62 installed in the chamber 61, and a high frequency power source 63 electrically connected to the electromagnetic coil 62. The etching apparatus 60 includes a magnetic lens 64 disposed around the chamber 61, a stage 65 disposed on the bottom of the chamber 61 and placing the SOI substrate 1 thereon, and an electrostatic chuck (see FIG. Not shown). The etching apparatus 60 includes a vacuum pump 66 that exhausts the chamber 61 and an electromagnetic valve 67 that opens and closes the vacuum pump 66.
As the plasma source, in addition to the above-mentioned ICP type, capacitively coupled plasma (CCP type: Capacitively-Coupled Plasma), electron cyclotron resonance plasma (ECP type: Electron-Coupled Plasma), microwave-excited surface wave plasma (SWP: Surface) Similar effects can be obtained by using Wave Plasma) or Helicon Wave Plasma (HWP).

The SOI substrate 1 is placed on the stage 65. The SOI substrate 1 is fixed to the stage 65 by an electrostatic chuck. For example, a DC voltage of 1000 to 2000 V is applied between the SOI substrate 1 and the electrostatic chuck, and the SOI substrate 1 is held by the electrostatic attractive force. The SOI substrate 1 is held by the mechanical clamp by mechanically holding the clamp (fixing jig) in contact with the outer peripheral portion of the SOI substrate 1.
Next, the vacuum pump 66 is operated to open and close the electromagnetic valve 67, thereby maintaining the interior of the chamber 61 at a desired degree of vacuum. Process gas is introduced into the chamber 61 and the high frequency power supply 63 is turned on. The process gas is excited by the high frequency of the electromagnetic coil 62, generates plasma, and generates radicals and ions. The radicals and ions etch the desired processed surface of the SOI substrate 1 to form the weight part 5a, the connection part 3b, and the frame part 5c. The above etching can be performed by using a generally manufactured ICP type dry etching apparatus. During etching, the SOI substrate 1 is supplied with a gas such as helium from the back side of the surface to be processed. The gas serves to cool the SOI substrate 1.

When the etching proceeds and the thickness of the support layer 3 is reduced, the connection portion 3b becomes a membrane supported by the BOX layer 4. Since this membrane is fragile, it may be damaged by electrostatic attraction when the SOI substrate 1 is released from the stage 65 after the etching is completed. In addition, the membrane may be damaged due to pressure fluctuations during the etching process and when the SOI substrate 1 is taken out of the chamber 61 and used in a transfer system (not shown).
However, in the present invention, the SOI substrate 1 having a membrane is protected by the protective layer 6, and damage to the membrane can be suppressed. In particular, when membrane breakage occurs during etching, the cooling gas leaks and the process performance deteriorates. In addition, it is possible to prevent the first layer from being corroded by the etching gas.

(5) Removal of protective layer (step S14 and FIG. 5 (g))
When the protective layer 6 is made of a water-soluble polymer material, the protective layer 6 is dissolved and removed by immersing the SOI substrate 1 in a separation liquid (for example, pure water). The time required for removal can be shortened by heating the separation liquid. Moreover, when a heat release sheet and a UV release sheet are used as the protective layer 6 as another aspect, the protective layer 6 can be removed by heating and UV light irradiation, respectively.

Next, the junction 4a is formed by etching a predetermined region of the BOX layer 4. That is, the BOX layer 4 is eroded with respect to the BOX layer 4 and is not eroded with respect to the active layer 3 and the support layer 5. Etch in the direction.
As such an etching method, for example, wet etching using buffered hydrofluoric acid (for example, a mixed aqueous solution of HF = 5.5 wt% and NH 4 F = 20 wt%) as an etchant can be cited.

(6) Bonding of glass substrate 2 (step S15 and FIG. 5 (h))
The SOI substrate 1 and the glass substrate 2 are bonded by anodic bonding. In a state where the glass substrate 2 and the frame portion 5b are brought into contact with each other and heated, a voltage is applied between them, so that the SOI substrate 1 and the glass substrate 2 are joined using the frame portion 5b as a contact, thereby integrating acceleration. The sensor 100 is manufactured.
As the glass substrate 2, a substrate made of the above-described material can be used. For example, when a substrate made of silicon or the like is used, the glass substrate 2 can be directly bonded to the SOI substrate.

  Thereafter, the acceleration sensor 100 is made into chips by dicing using a dicing saw or the like and separated into individual acceleration sensors. Such an acceleration sensor is generally called a piezoresistive acceleration sensor. Needless to say, the present invention can be applied to a capacitive acceleration sensor in addition to the piezoresistive acceleration sensor described in this embodiment.

Here, the structure etc. provided with the protective layer 6 and the thin plate-shaped flat support substrate which consists of a rigid body are demonstrated (FIG. 6 and FIG. 7). The support substrate is disposed so that the protective layer is sandwiched between the support substrate and the semiconductor substrate (SOI substrate), and the semiconductor substrate (SOI substrate) and the support substrate are bonded via the protective layer. A thin plate (wafer) made of a material such as silicon or glass. Furthermore, using the same material as the support layer 5, that is, using a silicon wafer is excellent in terms of productivity. In general, a wafer stage using an electrostatic chuck in a dry etching apparatus is selected according to the material of the wafer to be placed. Therefore, the stage must be replaced when manufacturing a mechanical quantity detection sensor made of a semiconductor material (mainly silicon). It is excellent in production efficiency. In the case where it is difficult to form a protective layer in the opening of the first structure body having a high aspect ratio, it is possible to prevent leakage of the cooling gas at the time of etching accompanying the membrane breakage, which is more preferable.

A description will be given, using the drawings, of a support substrate having a groove on the surface. FIG. 6A is a top view schematically showing a part of the support substrate 7, and FIG. 6B is a BB cross section in a state where the support substrate 7 and the SOI substrate 1 are bonded via the adhesive layer 7. FIG. The support substrate 7 is, for example, a support substrate having substantially the same diameter (for example, 10 cm to 20 cm) as the semiconductor substrate W, and the thickness thereof is, for example, 600 μm. As shown in FIG. 6A, the groove portion is, for example, a pattern in which grooves having a depth of 200 μm and a width of 1 mm are arranged in a grid pattern at a pitch of 1 mm. At this time, the ratio of the groove area in the surface of the support substrate 7 is about 75%.
When the groove portion 20 is formed in the support substrate 7 and the SOI substrate 1 and the support substrate 7 are bonded via the protective layer 6 made of, for example, a water-soluble polymer material, as shown in FIG. A cavity 30 is formed between the bottom surface and the adhesive layer. The hollow portion facilitates the entry of the separation liquid during the separation. The groove is preferably formed as a section having a high aspect ratio. In this case, the protective layer 6 does not reach the bottom of the groove, and a cavity is formed.
The groove 20 formed in the support substrate 7 can be formed by etching or sand blasting.

  As a pattern provided on the support substrate 7, an embodiment as shown in FIG. 6 can be used. In FIG. 7A, for example, through-holes 40 having a diameter of 200 μm (for example, a square having a side of 200 μm may be arranged) at a pitch of 1 mm. For example, a coupling portion 50 having a width of 50 μm and a depth of 200 μm is disposed to couple the through holes. The through hole is constituted by at least one adjacent portion and the coupling portion 50. During separation, the separation liquid can be easily penetrated from the through hole, and the separation liquid is spread in the surface of the support substrate by the coupling portion, so that a good separation operation can be obtained.

  Next, the structure and the manufacturing method of an angular velocity sensor according to another aspect of the mechanical quantity detection sensor according to the present embodiment and a manufacturing method thereof will be described (the same reference numerals are assigned to substantially the same configuration as the acceleration sensor). The aspects of the protective layer and the support substrate are substantially the same as the materials / conditions used in the method for manufacturing the acceleration sensor described above, and the description is omitted.

<Example 2>
FIG. 9 is an exploded perspective view showing a state where the angular velocity sensor 200 is disassembled. FIG. 10 is an exploded perspective view in which the semiconductor substrate in the mechanical quantity detection sensor of FIG. 9 is disassembled (the second layer is not shown for the sake of clarity).
The angular velocity sensor 200 includes a pair of support substrates (glass substrates) and a semiconductor substrate bonded by anodic bonding while being sandwiched between the pair of glass substrates. The semiconductor substrate is, for example, an SOI (Silicon On Insulator) substrate 1. In this case, the first, second, and third layers are an active layer, a BOX (buried oxide film) layer, and a support layer, respectively. The external quantity of the mechanical quantity detection sensor 100 is, for example, a substantially square shape with sides of 3 to 5 mm.
The SOI substrate 1 is formed by sequentially laminating a BOX layer 4 made of silicon dioxide and an active layer 3 made of silicon on a support layer 5 made of silicon. The active layer 3, the BOX layer 4, the support layer 5, and the glass substrate 2 have thicknesses of, for example, 5 to 100 μm, 1 to 5 μm, 300 to 800 μm, and 300 to 600 μm, respectively.

The active layer 3 includes a fixed portion 3c having an opening 3d, a displacement portion 3a disposed in the opening 3d and displaced with respect to the fixed portion 3c, and a connection for connecting the fixed portion 3c and the displacement portion 3a. It has a part (beam part) 3b and a block upper layer part 3e. The support layer 5 includes a weight part 5a joined to the displacement part 3a, a frame part 5b arranged around the weight part 5a and joined to the fixing part 3c, and a block lower layer part 5c. The BOX layer 4 has a joint portion 4a for joining the fixed portion 3d and the frame portion 5b, the displacement portion 3a and the weight portion 5a, and the block upper layer portion 3e and the block lower layer portion 5c, respectively (not shown for ease of viewing in FIG. 9). )
In FIG. 9 and FIG. 10, four connecting portions extend from the fixing portion 3c, and connect the fixing portion 3c and the displacement portion 3a. Four openings 3d exist around the displacement part 3a, and the block upper layer part 3e is disposed in the opening 3d.

FIG. 11 is a cross-sectional view showing a state where the mechanical quantity detection sensor 100 shown in FIG. 9 is cut along AA. A sealed chamber is formed by the upper and lower glass substrates 2, the fixing portion 3c, the joint portion 4a, and the frame portion 5b, and a detecting portion for detecting a mechanical quantity (angular velocity) acting from the outside is provided in the sealed chamber.
The displacement part 3a exists in a hollow state so as not to contact the glass substrate 2 by the connection part 3b in the sealed chamber. The weight portion 5a is joined to the displacement portion 3a, has a mass, and functions as a weight or an action body that receives Coriolis force due to angular velocity and inertial force due to acceleration. As shown in FIG. 10, the weight portion 5 a has, for example, a substantially clover shape as viewed in the vertical direction, and achieves both a reduction in size and high sensitivity of the sensor by distributing the mass.

  A driving electrode E1a and a detection electrode E2a are provided on the glass substrate 2 bonded to the fixed portion 3c and at a position facing the displacement portion 3a. Similarly, a driving electrode E1b and a detection electrode E2b are provided on the glass substrate 2 bonded to the frame portion 5b and at a position facing the mass portion 5a. Although not shown, E (drive electrode and detection electrode) is provided on the upper surface of the displacement portion 5a and the lower surface of the weight portion 5a. The driving electrodes E1 and E are capacitively coupled. When a voltage is applied between them, electrostatic attraction acts on the upper part of the displacement part 3a and the lower part of the mass part 5a, and the displacement part 3a (also the weight part 5a) is applied. It can be vibrated in the Z-axis direction.

  In a state where the displacement portion 3a is vibrated in the Z-axis direction, the angular velocity ωx is detected by detecting the displacement of the displacement portion 3a by the Y-axis or X-axis Coriolis forces Fy, Fx due to the angular velocity ωx, ωy in the X-axis or Y-axis direction. , Ωy can be measured. Thus, the angular velocity sensor 200 can measure the biaxial angular velocities ωx and ωy. The detection method and the like will be described later.

  The block upper layer portion 3e and the block lower layer portion 5e provided in the active layer 3 and the support layer 5 are used for wiring applications, respectively. The drive electrode E1a is electrically connected to the wiring terminal 17a by a wiring (not shown), the block lower layer portion 5e, the conduction portion 19, and the block upper layer portion 3e, and the upper surface of the displacement portion 3a when a voltage is applied to the wiring terminal 12a. Electrostatic attractive force acts on. Similarly, the drive electrode E1b is electrically connected to the wiring terminal 17b by a wiring (not shown) and the block lower layer part 5e, and when a voltage is applied to the wiring terminal 17b, electrostatic attraction acts on the lower surface of the weight part 5a. . In addition, the displacement part 3a and the weight part 5a are electrically connected by the conduction | electrical_connection part 19. FIG. The block part is used for wiring.

The principle of detection of the mechanical quantity by the angular velocity sensor 200 will be described.
(1) Vibration of the displacement portion 3a When a voltage is applied to the drive electrode E1a and the drive electrode E (not shown) on the upper surface of the displacement portion 3a, they attract each other by electrostatic attraction, and the displacement portion 3a (also the weight portion 5a) becomes Z Displacement in the axial positive direction. Similarly, when a voltage is applied to the drive electrode E1b and the drive electrode E (not shown) on the lower surface of the weight part 5a, they attract each other by electrostatic attraction, and the displacement part 3a (also the weight part 5a) is displaced in the negative direction of the Z axis. To do. That is, by alternately applying voltage, the displacement portion 3a (also the weight portion 5a) vibrates in the Z-axis direction. The voltage can be applied using a positive or negative direct current waveform (a pulse waveform when considering non-application), a half-wave waveform, or the like.

  The period of vibration of the displacement part 3a is determined by the period for switching the voltage. The switching cycle is preferably close to the natural frequency of the displacement portion 3a to some extent. The natural frequency of the displacement part 3a is determined by the elastic force of the connection part 3b, the mass of the weight part 5a, and the like. If the period of the vibration applied to the displacement part 3a does not correspond to the natural frequency, the energy of the vibration applied to the displacement part 3a is diffused and the energy efficiency is lowered.

  Note that an AC voltage having a frequency half that of the natural vibration of the displacement portion 3a is applied only between the drive electrodes E1a and E (not shown) or between the drive electrodes E1b and E (not shown). May be applied.

(2) Generation of mechanical quantity When the angular velocity ω is applied when the weight part 5a (displacement part 3a) is moving at the speed vz in the Z-axis direction, the Coriolis force F acts on the weight part 5a. Specifically, according to the angular velocity ωx in the X-axis direction and the angular velocity ωy in the Y-axis direction, the Coriolis force Fy (= 2 · m · vz · ωx) in the Y-axis direction and the Coriolis force Fx (= 2 · m · vz · ωy) acts on the weight part 5a (m is the mass of the weight part 5a).

  When the Coriolis force Fy due to the angular velocity ωx in the X-axis direction is applied, the displacement portion 3a is inclined in the Y direction. As described above, the Coriolis forces Fy and Fx resulting from the angular velocities ωx and ωy cause inclinations (displacements) in the Y direction and the X direction in the displacement portion 3a.

(3) Detection of displacement of the displacement portion 3a The inclination of the displacement portion 3a can be detected by the detection electrodes E2a and E2b. When Coriolis force is applied to the displacement portion 3a, the distance between the detection electrode E2a and the detection electrode E (not shown) provided on the upper surface of the displacement portion 3a, and the lower surface of the detection electrode E2b and the weight portion 5a The distance from the provided detection electrode E (not shown) changes, and as a result, the capacitance of both electrodes changes. That is, a change in the inclination of the displacement portion 3a can be detected based on this capacitance change (specifically, the capacitance difference between both electrodes) and taken out as a detection signal.

  As described above, the displacement part 3a is vibrated in the Z-axis direction by the driving electrode, and the inclinations of the displacement part 3a in the X and Y directions are detected by the detection electrode. As a result, it is possible to measure the angular velocities ωy and ωx in the X and Y directions (biaxial) by the mechanical quantity detection sensor 100.

(4) Separation of Detection Signal The signal output from the detection electrode is not only the component due to the angular velocities ωy and ωx applied to the weight part 5a. This signal includes components due to the accelerations αx and αy in the X-axis and Y-axis directions applied to the weight portion 5a. This is because the displacement of the displacement portion 5a can also occur due to the accelerations αx and αy.

  By detecting the DC component and AC component of the detection signal separately by an external electric circuit (not shown), the acceleration component and the angular velocity component can be measured independently. Thereby, the angular velocity can be detected.

A method for manufacturing the angular velocity sensor 200 will be described.
FIG. 12 is a flowchart showing an example of a procedure for creating the angular velocity sensor 200. 13 is a cross-sectional view showing a state of the angular velocity sensor 200 in the creation procedure of FIG. 12 (corresponding to a cross-sectional view taken along line AA in FIG. 9).

(1) Preparation of SOI substrate 1 (step S20 and FIG. 13 (a))
As shown in FIG. 13A, an SOI substrate 1 in which a BOX layer 4 and an active layer 3 are stacked on a support layer 5 is prepared. The SOI substrate 1 is produced by SIMOX or a bonding method.

  The active layer 3 and the support layer 5 contain impurities. Examples of impurities include boron. As silicon containing boron, for example, silicon containing high-concentration boron and having a resistivity of 0.001 to 0.01 Ω · cm can be used. Silicon containing impurities can be produced, for example, by doping boron in the production of a silicon single crystal by the Czochralski method.

(2) First structure formation (step S21 and FIG. 13B)
A resist mask having a pattern corresponding to the displacement portion 3a, the connection portion 3b, the fixing portion 3c, and the block upper layer portion 3e is provided on the upper surface of the active layer 3, and the active layer 3 is etched in the thickness direction, thereby forming the opening 3d. The displacement part 3a, the connection part 3b, and the fixed part 3c are formed. For example, by using such an etching method that has erosion with respect to the active layer 3 and does not have erosion with respect to the BOX layer 4 (or is lower than the erosion of the active layer 3). Is possible. Thus, etching is performed in the thickness direction until the upper surface of the BOX layer 4 is exposed to the opening 3d, thereby forming a first structure (FIG. 13B).

  As the above-described etching method, for example, dry etching by a RIE (Reactive Ion Etching) method using a mixed gas of CF 4 gas and O 2 gas can be used.

  In addition, a predetermined portion of the active layer 3 is etched to form a through hole 19 (a conductive portion 19 described later) that penetrates to the BOX layer 4. As an etching method, for example, 20% TMAH (tetramethylammonium hydroxide) can be used. For etching a BOX layer, for example, buffered hydrofluoric acid (for example, HF = 5.5 wt%, NH 4 F = 20 wt% mixed) Aqueous solution).

(3) Formation of protective layer (step S22 and FIG. 13 (c))
In accordance with the materials, methods, and configurations described in the method for manufacturing the acceleration sensor described above, description thereof is omitted here.

(4) Formation of second structure (step S23 and FIG. 13 (d))
A resist mask having a pattern corresponding to the weight part 5a, the frame part 5b, and the block lower layer part 5e is provided on the lower surface of the support layer 5, and the support layer 5 is etched in the thickness direction, thereby the weight part 5a, the frame part 5b, and the block lower layer part. 5e is formed. For example, by using such an etching method that has erosion with respect to the support layer 5 and does not have erosion with respect to the BOX layer 4 (or is lower than the erosion of the support layer 5). Is possible. Thus, the second structure is formed by etching in the thickness direction until the lower surface of the BOX layer 4 is exposed (FIG. 13D).

(5) Removal of protective layer (step S24 and FIG. 13 (e))
The description is omitted here in accordance with the method described in the method of manufacturing the acceleration sensor described above.

(6) Formation of electrodes (step S25 and FIG. 13 (e))
The through-hole 19 (conducting portion 19 described later) formed in the active layer 3 and the BOX layer 4, the displacement portion 3a upper surface, and the weight portion 5a lower surface are electrically connected to the conduction portion 19 by, for example, sputtering or vapor deposition. Electrode E (not shown) and detection electrode E (not shown) are formed. For example, Al, Cu, Ni, Au, Al—Nd, or the like can be used as the material for the electrodes and wiring.

The driving electrodes E1a and E1b and the detection electrodes E2a and E2b are formed on the glass substrate 2 and on the main surface facing the upper surface of the displacement portion 3a and the lower surface of the weight portion 5a by Al or Al-Nd by the above-described method. Etc. are used.
Moreover, in order to prevent the displacement part 3a from contacting the glass substrate 2, the recessed part (gap) is formed in the glass substrate 2 facing the upper surface of the displacement part 3a, and the drive electrode E1a, the detection electrode E2a, and A wiring (not shown) is formed.
Further, the glass substrate 2 facing the lower surface of the weight portion 5a is provided with a through hole (not shown) at a position corresponding to the wiring terminal 17, and by depositing the above metal into the through hole. The wiring terminal 17 is formed.

(7) Bonding of glass substrate 2 (step S26 and FIG. 13 (f))
The SOI substrate 1 and the two glass substrates 2 are bonded by, for example, anodic bonding.
The glass substrate 2 is preferably a glass substrate containing a large amount of mobile ions. For example, Pyrex (registered trademark) glass containing a large amount of Na ions can be used.

(8) Dicing (Step S27 and FIG. 13 (f))
A mechanical quantity detection sensor 200 composed of a pair of glass substrates 2 and an SOI substrate 1 bonded by anodic bonding in a state of being sandwiched between the pair of glass substrates 2 is diced with a dicing saw or the like. Separate into angular velocity sensors.

  As mentioned above, the manufacturing method of the above-mentioned mechanical quantity detection sensor is an example of the manufacturing method concerning the present invention, and is not restricted to the order of the above-mentioned step.

<Electronic parts using mechanical quantity detection sensor>
The mechanical quantity detection sensor according to the present invention is mounted on a circuit board on which an active element such as an IC is mounted, for example. The pad opening 17 and the wiring terminal 17 are connected to an active element such as an electronic circuit board or IC by a well-known method and material such as wire bonding connection, and functions as one electronic component. For example, the electronic component is mounted on a mobile terminal such as a game machine or a mobile phone and is distributed in the market.

It is a perspective view showing the acceleration sensor which is embodiment of this invention. It is a disassembled perspective view showing the acceleration sensor which is embodiment of this invention. It is a figure which shows the structure of the acceleration sensor of FIG. 1, Comprising: (a) Top view, (b) It is sectional drawing of AA in a top view. It is the flowchart which represented the preparation procedure of the acceleration sensor of FIG. 1 with the flowchart. It is sectional drawing showing an example of the manufacturing method of the acceleration sensor of FIG. It is a figure which shows typically the support substrate 7 used for embodiment of this invention, (a) It is a partial top view of the support substrate 7, (b) adheres to the SOI substrate 1 through the protective layer 7 It is a figure showing the BB cross section in the shape. It is a figure which shows another aspect of a support substrate typically, (A) is a partial top view of a support substrate, (B) is a figure which shows the cross section of a support substrate. It is the schematic of a general ICP type plasma etching apparatus. It is a disassembled perspective view showing the angular velocity sensor which concerns on this invention. It is the disassembled perspective view which decomposed | disassembled the SOI substrate in the angular velocity sensor of FIG. It is a figure which shows the structure of the angular velocity sensor of FIG. 9, Comprising: It is sectional drawing cut | disconnected along AA in FIG. FIG. 10 is a flowchart showing a manufacturing procedure of the angular velocity sensor of FIG. 9 in a flowchart. It is sectional drawing showing an example of the manufacturing method of the angular velocity sensor of FIG.

Explanation of symbols

100: Acceleration sensor 1: SOI substrate 2: Glass substrate 3: Active layer (first layer)
3a: Displacement part 3b: Connection part 3c: Fixed part 3d: Opening part 4: BOX layer (second layer)
4a: Joint part 5: Support layer (third layer)
5a: Weight part 5b: Frame part 6: Protective layer 7: Support substrate 11: Diffusion layer 12: Insulating layer 13: Contact hole 14: Interlayer connector 15: Wiring 16: Protective film 17: Pad opening 18: Through hole 19: Conductive parts Rx1 to Rx4, Ry1 to Ry4, Rz1 to Rz4: Piezoresistor 20: Groove part 30: Cavity part 40: Through hole 50: Coupling part 60: Plasma etching apparatus 61: Chamber 62: Electromagnetic coil 63: High frequency power supply 64: Magnetic field Lens 65: Stage 66: Vacuum pump 67: Electromagnetic valve W: Semiconductor substrate

200: Angular velocity sensor 1: SOI substrate 2: Glass substrate 3: Active layer (first layer)
3a: Displacement part 3b: Connection part 3c: Fixed part 3d: Opening part 3e: Block upper layer part 4: BOX layer (second layer)
4a: Joint part 5: Support layer (third layer)
5a: weight part 5b: frame part 5e: block lower layer part 17: wiring terminal 19: conduction part E: drive electrode, detection electrode E1a, E1b: drive electrode E2a, E2b: detection electrode

Claims (6)

Using a semiconductor substrate in which a first layer made of a semiconductor material, a second layer made of an insulating material, and a third layer made of a semiconductor material are sequentially laminated,
A first portion including a fixed portion having an opening in the first layer; a displacement portion disposed in the opening and displaced with respect to the fixed portion; and a connection portion connecting the fixed portion and the displacement portion. A first structure forming step of forming one structure;
A protective layer disposing step of providing a protective layer made of a water-soluble polymer material or an organic solvent-soluble polymer material on the first structure side;
The semiconductor substrate is integrally formed with the protective layer, and is etched in the thickness direction thereof to be bonded to the displacement portion by the third layer. The weight portion is disposed so as to surround the weight portion, and the fixing portion. a second structure forming step of forming a second structure comprising a frame portion joined to,
A protective layer removing step of removing the protective layer after the second structure forming step ,
In the protective layer disposing step, a support substrate made of a rigid plate that supports the semiconductor substrate is disposed so as to sandwich the protective layer between the support substrate and the semiconductor substrate, and the protective layer is disposed on the semiconductor substrate. Or provided in at least one of the support substrates, further comprising a step of disposing the semiconductor substrate and the support substrate so as to be bonded via the protective layer,
The support substrate has a groove on a surface facing the semiconductor substrate, a cavity is formed between the groove and the protective layer, and a separation liquid for removing the protective layer in the protective layer removing step is the cavity. A method for manufacturing a mechanical quantity detection sensor, characterized in that the sensor enters a magnetic field. Using a semiconductor substrate in which a first layer made of a semiconductor material, a second layer made of an insulating material, and a third layer made of a semiconductor material are sequentially laminated,
A first portion including a fixed portion having an opening in the first layer; a displacement portion disposed in the opening and displaced with respect to the fixed portion; and a connection portion connecting the fixed portion and the displacement portion. A first structure forming step of forming one structure;
A protective layer disposing step of providing a protective layer made of a water-soluble polymer material or an organic solvent-soluble polymer material on the first structure side;
The semiconductor substrate is integrally formed with the protective layer, and is etched in the thickness direction thereof to be bonded to the displacement portion by the third layer. The weight portion is disposed so as to surround the weight portion, and the fixing portion. A second structure forming step of forming a second structure including a frame portion bonded to
A protective layer removing step of removing the protective layer after the second structure forming step,
In the protective layer disposing step, a support substrate made of a rigid plate that supports the semiconductor substrate is disposed so as to sandwich the protective layer between the support substrate and the semiconductor substrate, and the protective layer is disposed on the semiconductor substrate. Or provided in at least one of the support substrates, further comprising a step of disposing the semiconductor substrate and the support substrate so as to be bonded via the protective layer,
  The method of manufacturing a mechanical quantity detection sensor, wherein the support substrate has a through hole, and a separation liquid for removing the protective layer enters the through hole in the protective layer removing step. The method of manufacturing a mechanical quantity detection sensor according to claim 2, wherein the support substrate includes a plurality of the through holes and a coupling portion that couples the through holes. 4. The method of manufacturing a mechanical quantity detection sensor according to claim 1, wherein the support substrate is a thin flat plate made of the same material as the third layer. 5. The method for producing a mechanical quantity detection sensor according to claim 1, wherein the separation liquid for removing the protective layer is heated and used. 6. The method of manufacturing a mechanical quantity detection sensor according to claim 1, wherein the mechanical quantity is acceleration or angular velocity.

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