JP2007127440A - Capacitive pressure sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a capacitive pressure sensor capable of acquiring the capacitive pressure sensor maintaining product characteristics and having high reliability. <P>SOLUTION: A glass substrate 11 having a fixed electrode and a silicon substrate 16 having a movable electrode are bonded so as to have a cavity 15 between the fixed electrode and the movable electrode, to thereby manufacture an aggregate having a plurality of capacitive pressure sensors. A dicing line provided between the capacitive pressure sensors in the aggregate is half-etched up to a deeper position than a position on a bonding surface 11e between the glass substrate 11 and the silicon substrate 16, and a protection layer 20 is formed so as to cover at least the side face of the capacitive pressure sensor in the half-etched domain, and dicing is performed along the dicing line, to thereby acquire the capacitive pressure sensor. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a capacitance-type pressure sensor that detects pressure using capacitance.

The capacitive pressure sensor joins a substrate having a pressure-sensitive diaphragm, which is a movable electrode, and a substrate having a fixed electrode so as to have a predetermined interval (cavity) between the pressure-sensitive diaphragm and the fixed electrode. It is constituted by. In this capacitance-type pressure sensor, when pressure is applied to the pressure-sensitive diaphragm, the pressure-sensitive diaphragm is deformed, thereby changing the distance between the pressure-sensitive diaphragm and the fixed electrode. The capacitance between the pressure-sensitive diaphragm and the fixed electrode changes due to the change in the interval, and a change in pressure is detected using the change in capacitance (for example, Patent Document 1).
Japanese Patent No. 2772111

  This capacitance type pressure sensor is usually manufactured by manufacturing a plurality of elements (capacitance type pressure sensor) on a wafer through a dicing line, and then dicing along a dicing line into a chip. The

  However, in such a method, a portion to be diced is exposed to a dicing cutter or a grinding fluid used for dicing. For this reason, grinding fluid or abrasive grains may enter from the interface between the substrates at the part to be diced, which may affect the capacitance type pressure sensor, leading to deterioration of product characteristics and reliability. There is. Further, in the post-cleaning cleaning process of the dicing process, since cleaning is performed under ultrasonic waves, penetration of a grinding fluid or polishing abrasive grains is promoted.

  This invention is made | formed in view of this point, and provides the manufacturing method of the capacitance-type pressure sensor which can obtain the capacitance-type pressure sensor which maintains a product characteristic and has high reliability. Objective.

  According to the method of manufacturing a capacitive pressure sensor of the present invention, a first substrate having a fixed electrode and a second substrate having a movable electrode are joined so as to have a predetermined interval between the fixed electrode and the movable electrode. A plurality of capacitance type pressure sensors, and a dicing line provided between the capacitance type pressure sensors in the assembly is formed between the first substrate and the second substrate. Half-etching to a position deeper than the position, forming a protective layer so as to cover at least the side surface of the capacitive pressure sensor in the half-etched region, and dicing along the dicing line And obtaining a capacitance type pressure sensor.

  According to this method, it is possible to prevent the grinding liquid, the abrasive grains, and the like from entering the capacitance type pressure sensor in the subsequent dicing process or cleaning process. Thereby, it is possible to obtain a capacitive pressure sensor that maintains product characteristics and has high reliability.

  In the method of manufacturing a capacitive pressure sensor according to the present invention, the first substrate is a glass substrate, the second substrate is a silicon substrate, and the first substrate and the second substrate are anodic bonded. It is preferable that According to this method, the airtightness of the cavity including the fixed electrode and the movable electrode can be maintained high, and a highly sensitive capacitive pressure sensor can be obtained.

  In the method of manufacturing a capacitive pressure sensor according to the present invention, in the step of producing the assembly having the plurality of capacitive pressure sensors, the protruding portion of the silicon substrate having the protruding portion is applied to the glass substrate. The silicon substrate and the glass substrate are polished so that the silicon substrate and the glass substrate are polished so that the silicon substrate is pressed against the glass substrate under heating, and the protruding portion penetrates the glass substrate. The fixed electrode is preferably embedded in a glass substrate. According to this method, it is possible to improve the airtightness in the cavity including the fixed electrode and the movable electrode, and to obtain a capacitive pressure sensor having high sensor sensitivity.

  According to the method of manufacturing a capacitive pressure sensor of the present invention, the first substrate having the fixed electrode and the second substrate having the movable electrode are arranged to have a predetermined distance between the fixed electrode and the movable electrode. And an assembly having a plurality of capacitance type pressure sensors is manufactured, and a dicing line provided between the capacitance type pressure sensors in the assembly is formed between the junction portions of the first and second substrates. Half-etching to a position deeper than the position, a protective layer is formed so as to cover at least the side surface of the capacitive pressure sensor in the half-etched region, and dicing is performed by dicing along the dicing line. Since the capacitance type pressure sensor is obtained, it is possible to obtain a capacitance type pressure sensor that maintains product characteristics and has high reliability.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
In the method for manufacturing a capacitive pressure sensor according to the present invention, the first substrate having the fixed electrode and the second substrate having the movable electrode are arranged to have a predetermined distance between the fixed electrode and the movable electrode. And an assembly having a plurality of capacitance type pressure sensors is manufactured, and a dicing line provided between the capacitance type pressure sensors in the assembly is formed between the junction portions of the first and second substrates. Half-etching to a position deeper than the position, a protective layer is formed so as to cover at least the side surface of the capacitive pressure sensor in the half-etched region, and dicing is performed by dicing along the dicing line. A capacitive pressure sensor is obtained.

  Regarding the first substrate and the second substrate, there is no particular limitation as long as the first substrate has a fixed electrode and the second substrate has a movable electrode. However, considering the characteristics of the capacitive pressure sensor, Preferably, one substrate is a glass substrate, the second substrate is a silicon substrate, and the first substrate and the second substrate are anodically bonded. According to such a configuration, the airtightness of the cavity including the fixed electrode and the movable electrode can be maintained high, and a highly sensitive capacitive pressure sensor can be obtained.

  In the method according to the present invention, a plurality of capacitance types are formed by joining a first substrate having a fixed electrode and a second substrate having a movable electrode so as to have a predetermined interval between the fixed electrode and the movable electrode. An assembly having a pressure sensor is produced. Each capacitive pressure sensor has a configuration shown in FIG. 2C, for example.

  In FIG. 2C, 11 indicates a glass substrate. The glass substrate 11 has a pair of main surfaces 11a and 11b facing each other. A first conductive member 12 that is a fixed electrode is embedded in a glass substrate 11 in a cavity 15 described later. Further, a second conductive member 13 that is a connection electrode for a movable electrode, which will be described later, is embedded in a region other than the cavity 15 of the glass substrate 11. The first and second conductive members 12 and 13 are exposed at the main surfaces 11a and 11b, respectively. On the main surface 11 a side of the first and second conductive members 12 and 13, recesses 11 c and 11 d for forming the cavities 15 and the electrodes 17 and 18 are formed.

  On the main surface 11b of the glass substrate 11, a lead electrode 14a is formed so as to be electrically connected to the exposed portion of the first conductive member 12, and is electrically connected to the exposed portion of the second conductive member 13. Thus, the extraction electrode 14b is formed. Since the lead electrodes 14a and 14b are provided on the main surface 11b as described above, the lead-out electrode to the outside can be formed on one surface, so that a device suitable for surface mounting can be obtained.

  On the exposed portions of the first and second conductive members 12 and 13 on the main surface 11a side, electrodes 17 and 18 for electrical connection with the movable electrode are formed by being laminated. In the present embodiment, the electrodes 17 and 18 are laminated, but the present invention is not limited to this, and the electrode may be provided as a single layer or three or more layers, and the second conductive member. 13 and a silicon substrate 16 described later may be directly joined.

  On the bonding surface 11d of the main surface 11a of the glass substrate 11, a silicon substrate 16 having a pressure-sensitive diaphragm 16a that is a movable electrode of the pressure sensor is bonded. By bonding the silicon substrate 16 having such a pressure sensitive diaphragm 16 a onto the main surface 11 a of the glass substrate 11, a cavity 15 is formed between the recess 11 c and the silicon substrate 16. As a result, a capacitance is generated between the pressure-sensitive diaphragm 16a (movable electrode) and the first conductive member 12 (fixed electrode).

  Note that the width of the recess 11c is desirably set to be larger than at least the width of the first conductive member 12 that is a fixed electrode. By setting in this way, when the first conductive member 12 is made of silicon, there is an interface between glass and silicon in the cavity 15 and there is no interface between other materials. The inside sealing performance can be improved.

  As a material constituting the first and second conductive members 12 and 13, a conductive material such as silicon or metal can be used, but the first conductive member 12 is sealed between the glass as described above. In consideration of the characteristics, it is preferable to use silicon. Note that a conductive material other than silicon may be used as the material constituting the first and second conductive members 12 and 13.

  The interface (bonding surface 11e) between the glass substrate 11 and the silicon substrate 16 preferably has high adhesion. When bonding the silicon substrate 16 to the glass substrate 11, the silicon substrate 16 is mounted on the bonding surface 11 e of the glass substrate 11, and an anodic bonding process is performed to increase the adhesion between the substrates 11 and 16. Can do. Thus, by exhibiting high adhesiveness at the interface between the glass substrate 11 and the silicon substrate 16, it is possible to maintain high airtightness in the cavity 15 formed between the silicon substrate 16 and the recess 11 c of the glass substrate 11. it can.

  Here, the anodic bonding treatment is performed by applying a predetermined voltage (for example, 300 V to 1 kV) at a predetermined temperature (for example, 400 ° C. or lower), thereby generating a large electrostatic attraction between silicon and glass, This refers to a treatment in which a chemical bond via oxygen is formed at the glass-silicon interface in contact, or a covalent bond is formed by releasing oxygen. The covalent bond at this interface is a Si—Si bond or a Si—O bond between the Si atom of silicon and the Si atom contained in the glass. Therefore, silicon and glass are firmly bonded by this Si—Si bond or Si—O bond, and very high adhesion is exhibited at the interface between the two. In order to perform such anodic bonding efficiently, the glass material of the glass substrate 11 is preferably a glass material containing an alkali metal such as sodium (for example, Pyrex (registered trademark) glass).

  When the first and / or second conductive members 12 and 13 are made of silicon, the interface between the glass substrate 11 and the first and / or second conductive members 12 and 13 is also anodic bonded. It is preferable. As will be described later, these interfaces are formed by pressing the first and / or second conductive members 12 and 13 into the glass substrate 11 under heating. Although high adhesion can be exhibited even at the interface obtained by such a method, the adhesion is improved by applying anodic bonding treatment after the first and / or second conductive members 12 and 13 are pushed into the glass substrate 11. Can be higher.

  In the capacitance-type pressure sensor having such a configuration, a predetermined capacitance is provided between the pressure-sensitive diaphragm 16a and the first conductive member 12 that is a fixed electrode in the glass substrate 11. When pressure is applied to the pressure sensor, the pressure sensitive diaphragm 16a is moved according to the pressure. As a result, the pressure sensitive diaphragm 16a is displaced. At this time, the electrostatic capacitance between the pressure sensitive diaphragm 16a and the fixed electrode in the glass substrate 11 changes. Therefore, the change can be a pressure change using the capacitance as a parameter.

  Half-etching is performed to a position deeper than the position of the joint between the first and second substrates, and a protective layer is formed so as to cover at least the side surface of the capacitive pressure sensor in the half-etched region. In this way, by forming a protective layer so as to cover at least the side surface of the capacitive pressure sensor, the grinding liquid and abrasive grains are allowed to pass through the capacitive pressure during the subsequent dicing process and cleaning process. It is possible to prevent erosion of each interface on the side surface of the sensor and penetration. Thereby, it is possible to obtain a capacitive pressure sensor that maintains product characteristics and has high reliability. In addition, the area | region which provides a protective layer is not limited to the side surface of an electrostatic capacitance type pressure sensor, It is preferable to provide in the area | region where a grinding fluid, an abrasive grain, etc. can penetrate | invade in an electrostatic capacitance type pressure sensor. As a half etching method, RIE (reactive ion etching) or the like can be used.

  As a method for forming the protective layer, a method capable of forming a thick film such as printing is preferable. Examples of the material constituting the protective layer include a resin material such as polyimide and an inorganic material such as glass in consideration of heat resistance and the like. These materials are preferable because the protective layer can be formed by a simple and low-cost process such as a printing process.

  In the method according to the present invention, in the step of producing an assembly having a plurality of capacitance-type pressure sensors, the silicon substrate is made of glass by bringing the protruding portion of the silicon substrate having the protruding portion into contact with the glass substrate. It is preferable to press the substrate under heating and polish the silicon substrate and the glass substrate so that the protruding portion penetrates the glass substrate, thereby embedding the protruding portion in the glass substrate to form a fixed electrode. According to this method, it is possible to improve the airtightness in the cavity including the fixed electrode and the movable electrode, and to obtain a capacitive pressure sensor having high sensor sensitivity.

  FIGS. 1A to 1E and FIGS. 2A to 2C are cross-sectional views for explaining a method of manufacturing a capacitive pressure sensor according to an embodiment of the present invention.

  First, a silicon substrate 17 having a low resistance by doping impurities is prepared. The impurity may be an n-type impurity or a p-type impurity. The resistivity is, for example, about 0.01 Ω · cm. Then, as shown in FIG. 1 (a), one main surface of the silicon substrate 17 is etched to form a protrusion 17a for the first conductive member 12 and a protrusion for the second conductive member 13 that become fixed electrodes. 17b is formed. In this case, a resist film is formed on the silicon substrate 17, and the resist film is patterned (photolithography) so that the resist film remains in the projecting portions 17a and 17b formation regions, and silicon is etched using the resist film as a mask. Thereafter, the remaining resist film is removed. In this way, the protrusions 17a and 17b are provided.

  Next, the glass substrate 11 is placed on the silicon substrate 17 on which the protrusions 17 a and 17 b are formed so that the protrusions 17 a and 17 b are in contact with the glass substrate 11. Further, the silicon substrate 17 and the glass substrate 11 are heated under vacuum, the silicon substrate 17 is pressed against the glass substrate 11, and the projecting portions 17 a and 17 b are pushed into the main surface 11 b of the glass substrate 11. ), The silicon substrate 17 and the glass substrate 11 are bonded to each other. The temperature at this time is not higher than the melting point of silicon and is preferably a temperature at which the glass can be deformed (for example, not higher than the softening point temperature of the glass). For example, the heating temperature is about 800 ° C.

  Furthermore, in order to further improve the adhesion at the interface between the protrusions 17a and 17b of the silicon substrate 17 and the glass substrate 11, it is preferable to perform an anodic bonding treatment. In this case, an electrode is attached to each of the silicon substrate 17 and the glass substrate 11 and a voltage of about 300 V to 1 kV is applied under heating at about 400 ° C. or lower. Thereby, the adhesiveness at the interface between the two becomes higher, and the airtightness of the cavity 15 of the capacitive pressure sensor can be improved.

  Next, as shown in FIG. 1B, the main surface 11 a side of the glass substrate 11 is polished to expose the protruding portions 17 a and 17 b of the silicon substrate 17. Next, as shown in FIG. 1C, the back surface (the side opposite to the glass substrate side) of the silicon substrate 17 is polished to expose the protruding portions 17a and 17b, and the first and second conductive members 12 and 13 are formed. Embedded in the glass substrate 11. Then, the glass substrate 11 and the protrusions 17a and 17b are milled, for example, to form a recess 11c for the cavity 15 and a recess 11d for the electrodes 17 and 18.

  Next, as shown in FIG. 1D, the electrodes 17 and 18 for the movable electrode are laminated and formed on the second conductive member 13 exposed in the recess 11d. In this case, first, an electrode material is deposited on the structure shown in FIG. 1C, a resist film is formed thereon, and the resist film is patterned (photographed so that the resist film remains in the electrode formation region). Lithography), the electrode material is etched using the resist film as a mask, and then the remaining resist film is removed. This process is performed twice to stack the electrodes 17 and 18. In addition, a lead electrode 14a for a fixed electrode and a lead electrode 14b for a movable electrode are formed on the back surface side (the side opposite to the electrodes 17 and 18) of the first conductive member 12. In this case, first, an electrode material is deposited on the back surface of the structure shown in FIG. 1C, a resist film is formed thereon, and the resist film is patterned so that the resist film remains in the lead electrode formation region. (Photolithography), the electrode material is etched using the resist film as a mask, and then the remaining resist film is removed.

  Next, as shown in FIG. 1 (e), a silicon substrate 16 previously formed to a predetermined thickness of about several tens of μm by etching or the like is connected to the first conductive member 12 whose pressure sensitive diaphragm 16a is a fixed electrode and a predetermined thickness. It joins on the joining surface 11e of the glass substrate 11 so that it may be located at intervals. At this time, an anodic bonding process is performed by applying a voltage of about 500 V to the silicon substrate 16 and the glass substrate 11 under heating at about 400 ° C. or less. Thereby, the adhesiveness at the interface between the silicon substrate 16 and the glass substrate 11 becomes higher, and the airtightness of the cavity 15 can be improved.

  Next, as shown in FIG. 2A, the dicing line is half-etched by RIE or the like to a position deeper than the position of the bonding surface 11e between the silicon substrate 16 and the glass substrate 11 to form the concave portion 19. This half etching is performed to a depth at which an interface for forming a protective layer described later is exposed. Here, there are an interface between the silicon substrate 16 and the electrode 18, an interface between the electrode 17 and the electrode 18, and an interface between the electrode 17 and the glass substrate 11. At such an interface, since it is assumed that a grinding fluid or the like enters in the dicing process, it is considered that a protective layer needs to be provided. Therefore, half etching is performed so as to expose such an interface. Note that the interface exposed by half-etching can be appropriately changed depending on the structure of the capacitive pressure sensor.

  Next, as shown in FIG. 2B, a protective layer 20 is formed so as to cover at least the side surface of the capacitive pressure sensor in the half-etched region, that is, the recess 19. As a material of the protective layer 20, a resin material such as polyimide is used and formed by a printing method or the like. According to such a method, the step of the concave portion 19 can be easily covered, and the protective layer can be formed with a thick film. In addition, the area | region which forms the protective layer 20 is an area | region where penetration | invasion of a grinding fluid etc. is assumed in a dicing process, and includes the side surface of an electrostatic capacitance type pressure sensor at least. This includes the interface between the silicon substrate 16 and the electrode 18 in FIG. 2, the interface between the electrode 17 and the electrode 18, and the interface between the electrode 17 and the glass substrate 11. In addition, the area | region which forms the protective layer 20 can be suitably changed with the structure of an electrostatic capacitance type pressure sensor similarly to the interface exposed by half etching.

  Next, as shown in FIG. 2C, dicing is performed along the dicing line, and the capacitive pressure sensor is formed into a chip. Thereafter, a capacitive pressure sensor is obtained through a cleaning process. About dicing, it is performed using the conditions usually performed, grinding fluid, etc.

  In the capacitive pressure sensor thus obtained, the first conductive member 12 as a fixed electrode is electrically connected to the extraction electrode 14a, and the pressure-sensitive diaphragm 16a is connected to the electrodes 17, 18 and the second conductive member 13. Is electrically connected to the extraction electrode 14b. Therefore, the capacitance change signal detected between the pressure-sensitive diaphragm 16a and the fixed electrode can be acquired from both the extraction electrodes 14a and 14b. The measured pressure can be calculated based on this signal. Capacitance type pressure sensor obtained by this method maintains the product characteristics and has high reliability because the ingress of grinding fluid and abrasive grains is prevented during the dicing process and cleaning process It is.

  The present invention is not limited to the embodiment described above, and can be implemented with various modifications. For example, the numerical values and materials described in the above embodiments are not particularly limited. Further, the process described in the above embodiment is not limited to this, and the process may be performed by changing the order as appropriate. Other modifications may be made as appropriate without departing from the scope of the object of the present invention.

  The present invention can be applied to, for example, a barometer that monitors atmospheric pressure or a capacitance-type pressure sensor that monitors gas pressure.

(A)-(e) is sectional drawing for demonstrating the manufacturing method of the capacitance-type pressure sensor which concerns on embodiment of this invention. (A)-(c) is sectional drawing for demonstrating the manufacturing method of the capacitance-type pressure sensor which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Glass substrate 11a, 11b Main surface 11c, 11d, 19 Recessed part 11e Joining surface 12, 13 Conductive member 14a, 14b Lead electrode 15 Cavity 16, 17 Silicon substrate 16a Pressure sensitive diaphragm 17, 18 Electrode 17a, 17b Protrusion part 20 Protective layer

Claims (3)

  An assembly having a plurality of capacitive pressure sensors obtained by joining a first substrate having a fixed electrode and a second substrate having a movable electrode so as to have a predetermined distance between the fixed electrode and the movable electrode. A step of half-etching a dicing line provided between the capacitance-type pressure sensors in the assembly to a position deeper than the position of the joint between the first and second substrates, and the half Forming a protective layer so as to cover at least a side surface of the capacitive pressure sensor in the etched region; obtaining a capacitive pressure sensor by performing dicing along the dicing line; A method of manufacturing a capacitive pressure sensor, comprising:   2. The electrostatic device according to claim 1, wherein the first substrate is a glass substrate, the second substrate is a silicon substrate, and the first substrate and the second substrate are anodically bonded. Manufacturing method of capacitive pressure sensor.   In the step of manufacturing the assembly having the plurality of capacitive pressure sensors, the silicon substrate is heated to the glass substrate so that the protrusion of the silicon substrate having the protrusion is brought into contact with the glass substrate. Pressing down and polishing the silicon substrate and the glass substrate so that the protruding portion penetrates the glass substrate, thereby embedding the protruding portion in the glass substrate to form the fixed electrode. The capacitive pressure sensor according to claim 2.

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