WO2007126269A1 - Touch mode capacitive pressure sensor - Google Patents

Touch mode capacitive pressure sensor Download PDF

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Publication number
WO2007126269A1
WO2007126269A1 PCT/KR2007/002094 KR2007002094W WO2007126269A1 WO 2007126269 A1 WO2007126269 A1 WO 2007126269A1 KR 2007002094 W KR2007002094 W KR 2007002094W WO 2007126269 A1 WO2007126269 A1 WO 2007126269A1
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WO
WIPO (PCT)
Prior art keywords
electrode
substrate
dielectric layer
lower electrode
pressure sensor
Prior art date
Application number
PCT/KR2007/002094
Other languages
French (fr)
Inventor
Bum-Kyoo Choi
Du-Hwan Choi
Original Assignee
Mdt Co.Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mdt Co.Ltd filed Critical Mdt Co.Ltd
Publication of WO2007126269A1 publication Critical patent/WO2007126269A1/en

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L9/00—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means
    • G01L9/0041—Transmitting or indicating the displacement of flexible diaphragms
    • G01L9/0072—Transmitting or indicating the displacement of flexible diaphragms using variations in capacitance
    • G01L9/0073—Transmitting or indicating the displacement of flexible diaphragms using variations in capacitance using a semiconductive diaphragm
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
    • G01D5/14—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage
    • G01D5/24—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying capacitance
    • G01D5/2403—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying capacitance by moving plates, not forming part of the capacitor itself, e.g. shields
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
    • H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
    • H01L29/84—Types of semiconductor device ; Multistep manufacturing processes therefor controllable by variation of applied mechanical force, e.g. of pressure

Definitions

  • the present invention relates to a touch mode capacitive pressure sensor, and more particularly, to a touch mode capacitive pressure sensor that is used for measuring a surrounding pressure and has a structure, in which the capacitance of the touch mode capacitive pressure sensor is increased according to the surrounding pressure, to thereby recognize the change in the surrounding pressure through the change in capacitance.
  • a capacitive pressure sensor has the same structure as that of a condenser having a shape in which a dielectric material is inserted between two electrodes that are parallel to each other.
  • the capacitance of the capacitive pressure sensor is determined according to an area of the two electrodes, a distance between the two electrodes and the dielectric constant of the dielectric material.
  • the change in surrounding pressure is detected through the capacitance that changed according to the distance between the two electrodes.
  • the characteristics of the capacitive pressure sensor are not largely changed although temperature changes.
  • the change in the distance between the two electrodes is small, the change in the capacitance is not large, and thus, it is difficult for the change in the surrounding pressure to be quantitatively detected by the capacitive pressure sensor.
  • the changes in the distance between the two electrodes to the capacitance according to the change in the surrounding pressure is a non-linear relationship, it is difficult for the surrounding pressure to be quantitatively detected by the capacitive pressure sensor.
  • FIG. 1 is a plan view of a touch mode capacitive pressure sensor according to an embodiment of the present invention
  • FIG. 2 is a cross-sectional view of the main parts of the touch mode capacitive i pressure sensor of FIG. 1 taken along line H-Il;
  • FIGS. 3 through 6 are cross-sectional views of a method of manufacturing the touch mode capacitive pressure sensor illustrated in FIG. 1 , according to an embodiment of the present invention
  • FIGS. 7 and 8 are cross-sectional views illustrating a change in shape of the touch mode capacitive pressure sensor according to surrounding pressure, as illustrated in FIG. 2;
  • FIG. 9 is a plan view of a lower electrode of a touch mode capacitive pressure sensor, according to another embodiment of the present invention.
  • FIG. 10 is a cross-sectional view of a touch mode capacitive pressure sensor according to another embodiment of the present invention.
  • electrode portion 221 lower electrode elements
  • the present invention provides a touch mode capacitive pressure sensor of which the change in its capacitance is large according to the change in surrounding pressure, and the changes in surrounding pressure to capacitance is a linear relationship.
  • a touch mode capacitive pressure sensor including: a substrate; a lower electrode formed on the substrate to cover a predetermined area of the substrate; a dielectric layer formed on the substrate to cover the lower electrode; and an upper electrode including a supporting portion having a ring shape, and which is disposed on the substrate to surround the lower electrode, and a conductive electrode portion that is supported by the supporting portion, hermetically seals an upper space of the lower electrode surrounded by the supporting portion, and is formed so as to contact the dielectric layer while elastically deforming due to an increase in pressure that is applied to a top surface of the supporting portion, wherein the electric capacitances of the upper electrode and the lower electrode are changed according to the amount of area of the electrode portion that contacts the dielectric layer.
  • the change in the capacitance of the capacitive pressure sensor is large according to the change in surrounding pressure so as to sensitively detect the change in the surrounding pressure, and thus, the change in the surrounding pressure can be easily and quantitatively detected by the capacitive pressure sensor.
  • a touch mode capacitive pressure sensor including: a substrate; a lower electrode formed on the substrate to cover a predetermined area of the substrate; a dielectric layer formed on the substrate to cover the lower electrode; and an upper electrode including a supporting portion having a ring shape, and which is disposed on the substrate to surround the lower electrode, and a conductive electrode portion that is supported by the supporting portion, hermetically seals an upper space of the lower electrode surrounded by the supporting portion, and is formed so as to contact the dielectric layer while elastically deforming due to an increase in pressure that is applied to a top surface of the supporting portion, wherein the electric capacitances of the upper electrode and the lower electrode are changed according to the amount of area of the electrode portion that contacts the dielectric layer.
  • FIG. 1 is a plan view of a touch mode capacitive pressure sensor 100 according to an embodiment of the present invention.
  • FIG. 2 is a cross-sectional view illustrating the main parts of the touch mode capacitive pressure sensor 100 of FIG. 1 taken along a line INI.
  • the touch mode capacitive pressure sensor 100 includes a substrate 10, a lower electrode 20, a dielectric layer 30 and an upper electrode 40.
  • the substrate 10 is formed of an insulating material such as pyrex glass.
  • the lower electrode 20 is configured in a structure in which a conductive metal
  • the dielectric layer 30 is formed to cover the lower electrode 20 formed on the substrate 10, and is formed of a metal having dielectricity.
  • the dielectric layer 30 may be formed of SiU2 material that is usually used in micro electro mechanical system (MEMS) technology, and is easily able to be deposited.
  • MEMS micro electro mechanical system
  • the upper electrode 40 includes a supporting portion 41 and an electrode portion 42.
  • the supporting portion 41 is formed on a top surface of the substrate 10, and is formed to have a square ring shape so as to surround the dielectric layer 30 and the lower electrode 20.
  • the electrode portion 42 is supported by the supporting portion 41 , and an upper space 7 of the lower electrode 20 that is surrounded by the supporting portion 41 is hermetically sealed by the upper electrode 40. Thus, the upper space 7 is formed between the electrode portion 42 and the dielectric layer 30.
  • the electrode portion 42 is formed of a conductive material. While the electrode portion 42 is elastically deformed according to the increase of a surrounding pressure that is applied on the top surface of the electrode portion 42, the electrode portion 42 contacts the dielectric layer 30.
  • the electrode portion 42 of the upper electrode 40 is formed of silicon (Si) to which boron (B) ions or phosphorus (P) ions are ion-implanted.
  • the silicon (Si) forming the electrode portion 42 of the upper electrode 40 is a non-conducting substance, and becomes conductive by the ion-implantation of the boron (B) ions or the phosphorus (P) ions.
  • the electrode portion 42 As a surrounding pressure that is applied to the top surface of the electrode portion 42 increases, the electrode portion 42 is elastically deformed, and thus, the amount of area of the electrode portion 42, which contacts the dielectric layer 30, is increased. On the other hand, as the surrounding pressure that is applied to the upper surface of the electrode portion 42 decreases, the electrode portion 42 is elastically restored to its original form. Thus, when the amount of area of the electrode portion 42, which contacts the dielectric layer 30, is decreased as the surrounding pressure further decreases, the electrode portion 42 does not contact the dielectric layer 30.
  • the touch mode capacitive pressure sensor 100 is manufactured using conventional MEMS technology.
  • the lower electrode 20, having a predetermined area is deposited on the substrate 10 formed of pyrex glass.
  • SiO 2 is deposited on the lower electrode 20 that is deposited on the substrate 10 in order to cover the lower electrode 20, and thus, the dielectric layer 30 is formed as shown in the structure of FIG. 3.
  • a concave shape for forming the upper space 7, which is hermetically sealed, is formed over the dielectric layer 30 by etching another substrate 50 formed of silicon (Si) so as to form the upper electrode 40.
  • boron (B) ions or phosphorus (P) ions are ion-implanted into the substrate 50, and thereby, permeating into the substrate 50 to a predetermined thickness, and thus, the substrate 50 becomes conductive.
  • the substrate 50 is reversibly illustrated in FIG. 4, and the substrate 50 is attached onto the substrate 10 formed of pyrex glass using an anodic bonding method to obtain the structure of FIG. 5. Using such anodic bonding method, the upper space
  • a voltage is applied between the upper electrode 40 and the lower electrode 20 in order to generate a potential difference therebetween.
  • the electrode portion 42 of the upper electrode 40 is separate from the dielectric layer 30, and the upper space 7 is formed between the electrode portion 42 and the dielectric layer 30, the upper electrode 40 and the lower electrode 20 are charged with a relatively low quantity of electric charges.
  • the electrode portion 42 of the upper electrode 40 elastically deforms due to the surrounding pressure that is applied on the electrode portion 42, and as such, a part of the electrode portion 42 of the upper electrode 40 contacts the dielectric layer 30, as illustrated in FIG. 7. Since the dielectric layer 30 has a relatively higher dielectricity than air, a part of the electrode portion 42 of the upper electrode 40, which contacts the dielectric layer 30, is charged with a large quantity of electric charges, and the lower electrode 20 facing the electrode portion 42 of the upper electrode 40 is also charged with the large quantity of electric charges.
  • the electrode portion 42 of the upper electrode 40 further deforms, and as such, the amount of area of the electrode portion 42 of the upper electrode 40 that contacts the dielectric layer 30 is further increased, as illustrated in FIG. 8. Due to the reasons as described above, the quantity of electric charges charging the upper electrode 40 and the lower electrode 20 are further increased.
  • the amount of area of the electrode portion 42 of the upper electrode 40, which contacts the dielectric layer 30, is increased in proportion to the increase in surrounding pressure, the electrical charges charging the upper electrode 40 and the lower electrode 20, that is, the capacitance of the touch mode capacitive pressure sensor 100 is also increased in proportion to the amount of contact area between the electrode portion 42 of the upper electrode 40 and the dielectric layer 30.
  • the electrode portion 42 of the upper electrode 40 is elastically restored, the amount of area of the electrode portion 42, which contacts the dielectric layer 30, decreases, and as such, the capacitance of the touch mode capacitive pressure sensor 100 decreases in proportion to the area.
  • the touch mode capacitive pressure sensor 100 is connected to an external circuit (not shown) that detects the capacitance of the touch mode capacitive pressure sensor 100 and converts the detected capacitance into pressure, and thus the surrounding pressure of a place, on which the touch mode capacitive pressure sensor 100 is equipped, can be easily measured.
  • the touch mode capacitive pressure sensor 100 measures a surrounding pressure using the change in the amount of contact area of the electrode portion 42 of the upper electrode 40, which contacts the dielectric layer 30, the change in the capacitance of the touch mode capacitive pressure sensor 100 is relatively large, and thus the capacitive pressure sensor 100 can be provided so as to have an increased sensitivity to a surrounding pressure.
  • the touch mode capacitive pressure sensor 100 is not limited thereto.
  • the lower electrode 22 may include a plurality of lower electrode elements 221 spaced apart from one another, as illustrated in FIG. 9.
  • a central part of the electrode portion 42 starts to contact the dielectric layer 30.
  • the central lower electrode elements 221 of the lower electrode elements 221 on the lower electrode 22 are sequentially charged by the electric charges. Accordingly, using an external circuit capable of detecting the change in the capacitance of each of the lower electrode elements 221 , and a pressure sensor outputting digitized input signals can be easily configured.
  • a touch mode capacitive pressure sensor 200 may be configured to have a structure as illustrated in FIG. 10.
  • a dielectric layer 31 is completely formed, so as to be wider than the dielectric layer 30 of the touch mode capacitive pressure sensor 100, on the substrate 10 so as to cover the lower electrode 20, and the supporting portion 61 of an upper electrode 60 is formed on the dielectric layer 31.
  • the supporting portion 61 of the upper electrode 60 is formed to have a ring shape only surrounding the lower electrode 20, the electrode portion 62 of the upper electrode 60 is formed to hermetically seal the space 8 surrounded by the dielectric layer 31 and the supporting portion 61 to be supported by the supporting portion 41. Even in this case, due to the increase in surrounding pressure, , the capacitance of the touch mode capacitive pressure sensor 200 is changed according to the amount of area of the electrode portion 62 of the upper electrode 60 that contacts the dielectric layer 31 as described above.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Ceramic Engineering (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • Computer Hardware Design (AREA)
  • Measuring Fluid Pressure (AREA)
  • Pressure Sensors (AREA)

Abstract

Provided is a touch mode capacitive pressure sensor including a substrate, a lower electrode formed on the substrate to cover a predetermined area of the substrate, a dielectric layer formed on the substrate to cover the lower electrode, and an upper electrode comprising a supporting portion having a ring shape, and which is disposed on the substrate to surround the lower electrode, and a conductive electrode portion that is supported by the supporting portion, hermetically seals an upper space of the lower electrode surrounded by the supporting portion, and is formed so as to contact the dielectric layer while elastically deforming due to increase in pressure that is applied to a top surface of the supporting portion, wherein the electric capacitances of the upper electrode and the lower electrode are changed according to the amount of area of the electrode portion, that contacts the dielectric layer.

Description

TOUCH MODE CAPACITIVE PRESSURE SENSOR
TECHNICAL FIELD The present invention relates to a touch mode capacitive pressure sensor, and more particularly, to a touch mode capacitive pressure sensor that is used for measuring a surrounding pressure and has a structure, in which the capacitance of the touch mode capacitive pressure sensor is increased according to the surrounding pressure, to thereby recognize the change in the surrounding pressure through the change in capacitance.
BACKGROUND ART
Conventionally, a capacitive pressure sensor has the same structure as that of a condenser having a shape in which a dielectric material is inserted between two electrodes that are parallel to each other. The capacitance of the capacitive pressure sensor is determined according to an area of the two electrodes, a distance between the two electrodes and the dielectric constant of the dielectric material. The change in surrounding pressure is detected through the capacitance that changed according to the distance between the two electrodes. The characteristics of the capacitive pressure sensor are not largely changed although temperature changes. However, since the change in the distance between the two electrodes is small, the change in the capacitance is not large, and thus, it is difficult for the change in the surrounding pressure to be quantitatively detected by the capacitive pressure sensor. In addition, since the changes in the distance between the two electrodes to the capacitance according to the change in the surrounding pressure is a non-linear relationship, it is difficult for the surrounding pressure to be quantitatively detected by the capacitive pressure sensor.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a plan view of a touch mode capacitive pressure sensor according to an embodiment of the present invention;
FIG. 2 is a cross-sectional view of the main parts of the touch mode capacitive i pressure sensor of FIG. 1 taken along line H-Il;
FIGS. 3 through 6 are cross-sectional views of a method of manufacturing the touch mode capacitive pressure sensor illustrated in FIG. 1 , according to an embodiment of the present invention; FIGS. 7 and 8 are cross-sectional views illustrating a change in shape of the touch mode capacitive pressure sensor according to surrounding pressure, as illustrated in FIG. 2;
FIG. 9 is a plan view of a lower electrode of a touch mode capacitive pressure sensor, according to another embodiment of the present invention; and FIG. 10 is a cross-sectional view of a touch mode capacitive pressure sensor according to another embodiment of the present invention.
< Explanation of Reference numerals designating the Major Elements of the Drawings>
100; touch mode capacitive pressure sensor 10; substrate 20; lower electrode 30; dielectric layer
40; upper electrode 41 ; supporting portion
42; electrode portion 221 ; lower electrode elements
DETAILED DESCRIPTION OF THE INVENTION
TECHNICAL PROBLEM
The present invention provides a touch mode capacitive pressure sensor of which the change in its capacitance is large according to the change in surrounding pressure, and the changes in surrounding pressure to capacitance is a linear relationship.
TECHNICAL SOLUTION
According to an aspect of the present invention, there is provided a touch mode capacitive pressure sensor including: a substrate; a lower electrode formed on the substrate to cover a predetermined area of the substrate; a dielectric layer formed on the substrate to cover the lower electrode; and an upper electrode including a supporting portion having a ring shape, and which is disposed on the substrate to surround the lower electrode, and a conductive electrode portion that is supported by the supporting portion, hermetically seals an upper space of the lower electrode surrounded by the supporting portion, and is formed so as to contact the dielectric layer while elastically deforming due to an increase in pressure that is applied to a top surface of the supporting portion, wherein the electric capacitances of the upper electrode and the lower electrode are changed according to the amount of area of the electrode portion that contacts the dielectric layer.
ADVANTAGEOUS EFFECTS
Due to an improvement in the structure of a capacitive pressure sensor, the change in the capacitance of the capacitive pressure sensor is large according to the change in surrounding pressure so as to sensitively detect the change in the surrounding pressure, and thus, the change in the surrounding pressure can be easily and quantitatively detected by the capacitive pressure sensor.
BEST MODE
According to an aspect of the present invention, there is provided a touch mode capacitive pressure sensor including: a substrate; a lower electrode formed on the substrate to cover a predetermined area of the substrate; a dielectric layer formed on the substrate to cover the lower electrode; and an upper electrode including a supporting portion having a ring shape, and which is disposed on the substrate to surround the lower electrode, and a conductive electrode portion that is supported by the supporting portion, hermetically seals an upper space of the lower electrode surrounded by the supporting portion, and is formed so as to contact the dielectric layer while elastically deforming due to an increase in pressure that is applied to a top surface of the supporting portion, wherein the electric capacitances of the upper electrode and the lower electrode are changed according to the amount of area of the electrode portion that contacts the dielectric layer.
Preferred embodiments of the present invention will now be described with reference to the attached drawings. FIG. 1 is a plan view of a touch mode capacitive pressure sensor 100 according to an embodiment of the present invention. FIG. 2 is a cross-sectional view illustrating the main parts of the touch mode capacitive pressure sensor 100 of FIG. 1 taken along a line INI. Referring to FIGS. 1 and 2, the touch mode capacitive pressure sensor 100 includes a substrate 10, a lower electrode 20, a dielectric layer 30 and an upper electrode 40.
The substrate 10 is formed of an insulating material such as pyrex glass. The lower electrode 20 is configured in a structure in which a conductive metal
(e.g., aluminum and copper) covers a predetermined area of a top surface of the substrate 10.
The dielectric layer 30 is formed to cover the lower electrode 20 formed on the substrate 10, and is formed of a metal having dielectricity. In particular, the dielectric layer 30 may be formed of SiU2 material that is usually used in micro electro mechanical system (MEMS) technology, and is easily able to be deposited.
The upper electrode 40 includes a supporting portion 41 and an electrode portion 42.
The supporting portion 41 is formed on a top surface of the substrate 10, and is formed to have a square ring shape so as to surround the dielectric layer 30 and the lower electrode 20.
The electrode portion 42 is supported by the supporting portion 41 , and an upper space 7 of the lower electrode 20 that is surrounded by the supporting portion 41 is hermetically sealed by the upper electrode 40. Thus, the upper space 7 is formed between the electrode portion 42 and the dielectric layer 30. The electrode portion 42 is formed of a conductive material. While the electrode portion 42 is elastically deformed according to the increase of a surrounding pressure that is applied on the top surface of the electrode portion 42, the electrode portion 42 contacts the dielectric layer 30. The electrode portion 42 of the upper electrode 40 is formed of silicon (Si) to which boron (B) ions or phosphorus (P) ions are ion-implanted. The silicon (Si) forming the electrode portion 42 of the upper electrode 40 is a non-conducting substance, and becomes conductive by the ion-implantation of the boron (B) ions or the phosphorus (P) ions.
As a surrounding pressure that is applied to the top surface of the electrode portion 42 increases, the electrode portion 42 is elastically deformed, and thus, the amount of area of the electrode portion 42, which contacts the dielectric layer 30, is increased. On the other hand, as the surrounding pressure that is applied to the upper surface of the electrode portion 42 decreases, the electrode portion 42 is elastically restored to its original form. Thus, when the amount of area of the electrode portion 42, which contacts the dielectric layer 30, is decreased as the surrounding pressure further decreases, the electrode portion 42 does not contact the dielectric layer 30.
Hereinafter, a method of manufacturing the touch mode capacitive pressure sensor 100 will be described in detail.
The touch mode capacitive pressure sensor 100 is manufactured using conventional MEMS technology.
First, the lower electrode 20, having a predetermined area, is deposited on the substrate 10 formed of pyrex glass. SiO2 is deposited on the lower electrode 20 that is deposited on the substrate 10 in order to cover the lower electrode 20, and thus, the dielectric layer 30 is formed as shown in the structure of FIG. 3.
As illustrated in FIG. 4, a concave shape for forming the upper space 7, which is hermetically sealed, is formed over the dielectric layer 30 by etching another substrate 50 formed of silicon (Si) so as to form the upper electrode 40.
As shown by dotted line of FIG. 4, boron (B) ions or phosphorus (P) ions are ion-implanted into the substrate 50, and thereby, permeating into the substrate 50 to a predetermined thickness, and thus, the substrate 50 becomes conductive.
The substrate 50 is reversibly illustrated in FIG. 4, and the substrate 50 is attached onto the substrate 10 formed of pyrex glass using an anodic bonding method to obtain the structure of FIG. 5. Using such anodic bonding method, the upper space
7 is formed between the dielectric layer 30 and the electrode portion 42 of the upper electrode 40.
Likewise, lapping is performed on the substrate 50 of the structure of FIG. 5, and the substrate 50 is planed to a predetermined degree as illustrated in FIG. 6 so as to be etched. Then, only the upper electrode 40, into which boron (B) ions or phosphorus
(P) ions have permeated, remains on the substrate 10. As a result, the touch mode capacitive pressure sensor 100 of FIG. 2 is completed.
Hereinafter, a function of the touch mode capacitive pressure sensor 100 will be described.
First, a voltage is applied between the upper electrode 40 and the lower electrode 20 in order to generate a potential difference therebetween. At this time, since the electrode portion 42 of the upper electrode 40 is separate from the dielectric layer 30, and the upper space 7 is formed between the electrode portion 42 and the dielectric layer 30, the upper electrode 40 and the lower electrode 20 are charged with a relatively low quantity of electric charges.
In such state, as a surrounding pressure increases, the electrode portion 42 of the upper electrode 40 elastically deforms due to the surrounding pressure that is applied on the electrode portion 42, and as such, a part of the electrode portion 42 of the upper electrode 40 contacts the dielectric layer 30, as illustrated in FIG. 7. Since the dielectric layer 30 has a relatively higher dielectricity than air, a part of the electrode portion 42 of the upper electrode 40, which contacts the dielectric layer 30, is charged with a large quantity of electric charges, and the lower electrode 20 facing the electrode portion 42 of the upper electrode 40 is also charged with the large quantity of electric charges.
Again, as the surrounding pressure further increases, the electrode portion 42 of the upper electrode 40 further deforms, and as such, the amount of area of the electrode portion 42 of the upper electrode 40 that contacts the dielectric layer 30 is further increased, as illustrated in FIG. 8. Due to the reasons as described above, the quantity of electric charges charging the upper electrode 40 and the lower electrode 20 are further increased.
Likewise, when the amount of area of the electrode portion 42 of the upper electrode 40, which contacts the dielectric layer 30, is increased in proportion to the increase in surrounding pressure, the electrical charges charging the upper electrode 40 and the lower electrode 20, that is, the capacitance of the touch mode capacitive pressure sensor 100 is also increased in proportion to the amount of contact area between the electrode portion 42 of the upper electrode 40 and the dielectric layer 30. On the other hand, as the surrounding pressure decreases, the electrode portion 42 of the upper electrode 40 is elastically restored, the amount of area of the electrode portion 42, which contacts the dielectric layer 30, decreases, and as such, the capacitance of the touch mode capacitive pressure sensor 100 decreases in proportion to the area. The touch mode capacitive pressure sensor 100 is connected to an external circuit (not shown) that detects the capacitance of the touch mode capacitive pressure sensor 100 and converts the detected capacitance into pressure, and thus the surrounding pressure of a place, on which the touch mode capacitive pressure sensor 100 is equipped, can be easily measured. In addition, as compared to a capacitive pressure sensor measuring a pressure using a change in a distance between two electrodes including a dielectric layer therebetween, since the touch mode capacitive pressure sensor 100 measures a surrounding pressure using the change in the amount of contact area of the electrode portion 42 of the upper electrode 40, which contacts the dielectric layer 30, the change in the capacitance of the touch mode capacitive pressure sensor 100 is relatively large, and thus the capacitive pressure sensor 100 can be provided so as to have an increased sensitivity to a surrounding pressure.
In addition, in proportion to the increase in the amount of contact area of the electrode portion 42 of the upper electrode 40, with the dielectric layer 30, since the capacitance of the touch mode capacitive pressure sensor 100 is increased, the changes in surrounding pressure to the capacitance is a linear relationship. Accordingly, the surrounding pressure can be easily calculated from the capacitance of the touch mode capacitive pressure sensor 100.
MODE OF THE INVENTION
Although the embodiment of the present invention has been described, the touch mode capacitive pressure sensor 100 is not limited thereto.
For example, the lower electrode 22 may include a plurality of lower electrode elements 221 spaced apart from one another, as illustrated in FIG. 9. In this case, as an electrode portion 42 of an upper electrode 40 elastically deforms according to the increase in surrounding pressure and contact the dielectric layer 30, a central part of the electrode portion 42 starts to contact the dielectric layer 30. Accordingly, the central lower electrode elements 221 of the lower electrode elements 221 on the lower electrode 22 are sequentially charged by the electric charges. Accordingly, using an external circuit capable of detecting the change in the capacitance of each of the lower electrode elements 221 , and a pressure sensor outputting digitized input signals can be easily configured.
In addition, even if the supporting portion 41 of the upper electrode 40 is formed on the top surface of a substrate 10 so as to surround the dielectric layer 30 and the lower electrode 20, a touch mode capacitive pressure sensor 200, according to another embodiment of the present invention, may be configured to have a structure as illustrated in FIG. 10. In the touch mode capacitive pressure sensor 200, a dielectric layer 31 is completely formed, so as to be wider than the dielectric layer 30 of the touch mode capacitive pressure sensor 100, on the substrate 10 so as to cover the lower electrode 20, and the supporting portion 61 of an upper electrode 60 is formed on the dielectric layer 31. In this case, the supporting portion 61 of the upper electrode 60 is formed to have a ring shape only surrounding the lower electrode 20, the electrode portion 62 of the upper electrode 60 is formed to hermetically seal the space 8 surrounded by the dielectric layer 31 and the supporting portion 61 to be supported by the supporting portion 41. Even in this case, due to the increase in surrounding pressure, , the capacitance of the touch mode capacitive pressure sensor 200 is changed according to the amount of area of the electrode portion 62 of the upper electrode 60 that contacts the dielectric layer 31 as described above.

Claims

1. A touch mode capacitive pressure sensor comprising: a substrate; a lower electrode formed on the substrate to cover a predetermined area of the substrate; a dielectric layer formed on the substrate to cover the lower electrode; and an upper electrode comprising a supporting portion having a ring shape, and which is disposed on the substrate to surround the lower electrode, and a conductive electrode portion that is supported by the supporting portion, hermetically seals an upper space of the lower electrode surrounded by the supporting portion, and is formed so as to contact the dielectric layer while elastically deforming due to an increase in pressure that is applied to a top surface of the supporting portion, wherein the electric capacitances of the upper electrode and the lower electrode are changed according to the amount of area of the electrode portion that contacts the dielectric layer.
2. The sensor of claim 1 , wherein the dielectric layer is formed on the substrate so as to cover the lower electrode, and the supporting portion of the upper electrode is formed on the substrate so as to surround the dielectric layer and the lower electrode.
3. The sensor of claim 1 , wherein the supporting portion of the upper electrode is formed to contact a top surface of the dielectric layer.
4. The sensor of any one of claims 1 through 3, wherein the lower electrode comprises a plurality of lower electrode elements spaced apart from one another.
5. The sensor of any one of claims 1 through 3, wherein the electrode portion of the upper electrode becomes conductive by an ion-implantation of boron (B) ions or phosphorus (P) ions into silicon (Si).
6. The sensor of any one of claims 1 through 3, wherein the dielectric layer is formed of a SiO2 material.
PCT/KR2007/002094 2006-04-28 2007-04-27 Touch mode capacitive pressure sensor WO2007126269A1 (en)

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KR1020060038846A KR20070106225A (en) 2006-04-28 2006-04-28 Touch mode capacitive pressure sensor
KR10-2006-0038846 2006-04-28

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