JP2010008045A - Sensor and measuring apparatus and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sensor capable of accurately measuring the gas species, pressure, or quantity of flow of gas. <P>SOLUTION: The sensor includes a semiconductor layer 13 of which the surface is in thermal contact with a gas to be measured; a heater 131 for heating the semiconductor layer 13; and a temperature detection element (diode) D1 which is embedded in the upper part of the semiconductor layer 13 for detecting the temperature of the semiconductor layer 13 before and after being heated by the heater 131. The gas species, pressure, or quantity of flow of the gas is measured on the basis of the temperature difference of the semiconductor layer 13 before and after its heating. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a sensor for measuring gas pressure and the like, and further relates to a measuring apparatus and a measuring method using the sensor.

  As a sensor for measuring the gas type, pressure or flow rate of the gas in the chamber, the fact that the temperature difference detected by the two temperature detection elements (diodes) is proportional to the gas type, pressure or flow rate of the gas in the chamber was used. A sensor is known (for example, refer to Patent Document 1). That is, one temperature detection element is arranged in the vicinity of the heater to detect the temperature of the heater and control the heater to a constant temperature. The other temperature detection element is arranged so as to be in thermal contact with the gas and in contact with the gas to detect the temperature in the chamber. From the temperature difference detected by the two temperature detection elements, the pressure of the gas in the chamber is measured with reference to calibration curve data for the pressure of the gas in the chamber obtained in advance.

However, when the temperature detection element thermally separated from the heater detects the temperature in the chamber, the temperature in the chamber fluctuates due to the water temperature of the chiller unit arranged outside the chamber, and the gas in the chamber The gas type, pressure or flow rate may not be measured accurately.
JP 2006-153769 A

  An object of the present invention is to provide a sensor, a measuring apparatus, and a measuring method capable of accurately measuring the gas type, pressure, or flow rate of a gas.

  According to one aspect of the present invention, (a) a semiconductor layer whose surface is in thermal contact with a gas to be measured, (b) a heater for heating the semiconductor layer, and (c) embedded in an upper portion of the semiconductor layer. And a temperature detecting element for detecting the temperature of the semiconductor layer before and after heating by the heater, and a sensor for measuring the gas type, pressure, or flow rate of the gas from the temperature difference between the semiconductor layers before and after heating is provided.

  According to another aspect of the present invention, (a) a semiconductor layer whose surface is in thermal contact with a gas to be measured, a heater for heating the semiconductor layer, and a heater embedded in the upper portion of the semiconductor layer and heated by the heater (B) The temperature difference between the semiconductor layers before and after heating is input from the temperature detection element, and the gas type, pressure, or flow rate of the gas is calculated. And a measuring device.

  According to another aspect of the present invention, (a) a step of heating the semiconductor layer whose surface is in thermal contact with the gas to be measured by a heater, and (b) the temperature of the semiconductor layer before and after the heating by the heater. There is provided a measurement method including a step of detecting by a temperature detection element embedded in an upper portion of a semiconductor layer, and (c) converting a current or voltage from the detection element into a gas species, pressure, or flow rate of gas .

  According to the present invention, it is possible to provide a sensor, a measuring apparatus, and a measuring method capable of accurately measuring the gas type, pressure, or flow rate of gas.

  Next, embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic, and the relationship between the thickness and the planar dimensions, the ratio of the thickness of each layer, and the like are different from the actual ones. Therefore, specific thicknesses and dimensions should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

  Further, the embodiments described below exemplify apparatuses and methods for embodying the technical idea of the present invention, and the technical idea of the present invention includes the material, shape, structure, The layout is not specified as follows. The technical idea of the present invention can be variously modified within the scope of the claims.

  FIG. 1 shows a plan view of a sensor (sensor chip) 1 of the measuring apparatus according to the embodiment of the present invention, and FIG. 2 shows a corresponding cross-sectional view. FIG. 2 is a cross-sectional structure of the sensor 1 shown in FIG. 1 as viewed from the AA direction, and FIG. 2 will be described first.

As shown in FIG. 2, the sensor 1 includes a first conductivity type (p-type) semiconductor layer (SOI layer) 13 whose surface is in thermal contact with a gas to be measured, and an upper portion of the semiconductor layer 13. A semiconductor resistance region (heater) 131 of the second conductivity type (n ⁺ type) that heats the semiconductor layer 13 and a semiconductor resistance region (heater) 131 embedded in the upper part of the semiconductor layer 13 apart from the semiconductor resistance region. A temperature detection element (diode) D1 that detects the temperature of the semiconductor layer 13 before and after being heated by the (heater) 131 is provided. Temperature detecting element D1 has an anode region 132 made of a semiconductor of a first conductivity type (p ⁺ -type), and the cathode region 133 made of a semiconductor of a second conductivity type formed around the anode region 132 (n ⁺ -type) Consists of.

  The “first conductivity type” and the “second conductivity type” are opposite conductivity types. That is, if the first conductivity type is n-type, the second conductivity type is p-type. If the first conductivity type is p-type, the second conductivity type is n-type. Accordingly, here, the case where the first conductivity type is p-type and the second conductivity type is n-type will be described as an example. However, even if the first conductivity type is n-type and the second conductivity type is p-type, It can be easily understood that the same effect can be obtained if the polarities are reversed.

  The semiconductor layer 13 is provided on a buried insulating film (BOX layer) 12 disposed on the support substrate 11. As a material for the support substrate 11 and the semiconductor layer 13, silicon (Si) or the like can be used.

The semiconductor resistance region 131 is connected to the heater electrodes 15a and 15d through the opening of the field insulating film 14 such as a thermal oxide film (SiO ₂ film). The anode region 132 is connected to the sensor electrode 15 b through the opening of the field insulating film 14. The cathode region 133 is connected to the sensor electrode 15 c through the opening of the field insulating film 14. Aluminum (Al) or the like can be used as a material for the heater electrodes 15a and 15d and the sensor electrodes 15b and 15c.

  The semiconductor resistance region 131 forms a pn junction with the surrounding semiconductor layer 13 and is separated from the pn junction. When a current is passed through the heater electrodes 15a and 15d under a bias condition in which the pn junction is reverse-biased, a current can be passed only through the semiconductor resistance region 131, and only the semiconductor resistance region 131 can be Joule-heated. The temperature detection element (diode) D1 is applied with a constant voltage in the forward direction, and flows a current (current signal) corresponding to the temperature of the semiconductor layer 13. This current signal, on-resistance change, rise voltage change (diffusion potential), or the like is detected as the temperature of the semiconductor layer 13.

Although not shown, the field insulating film 14, the heater electrode 15a, 15d and the sensor electrode 15b, on the whole 15c, the oxidation film (SiO ₂ film), a nitride film (SiN film), or PSG A protective film (passivation film) such as a film is coated. The film thickness of the protective film is preferably thin enough that thermal resistance can be ignored in consideration of sensor sensitivity. On the step cross section viewed from the AA direction in FIG. 1, the central portion and the peripheral portion of the sensor 1 are separated by a gap 17. In addition, on the cross section of the staircase viewed from the AA direction, a gap 17 is formed under the BOX layer 12 in the center of the sensor 1.

  As shown in FIG. 1, as the planar pattern, the peripheral portion is formed in a frame shape and is arranged so as to surround the periphery of the central portion. As a cross-sectional view, the peripheral portion and the central portion are connected by a beam having a laminated structure including a BOX layer 12, a semiconductor layer 13, and a field insulating film 14 as shown in FIG. As shown in FIG. 1, heater electrodes 15a and 15d and sensor electrodes 15b and 15c extend on the field insulating film 14 of the beam. The heater electrodes 15a and 15d are connected to heater electrode pads 16a and 16d arranged in the periphery, respectively. The sensor electrodes 15b and 15c are connected to sensor electrode pads 16b and 16c arranged in the peripheral portion, respectively. In the central portion, the semiconductor resistance region 131 is arranged, for example, in a ring shape around the anode region 132 and the cathode region 133.

  As shown in FIG. 3, the sensor 1 is disposed in a chamber 2 that houses a gas to be measured. A gas to be measured is filled in the chamber 2 at a specific gas pressure or is flowed at a specific gas flow rate. The sensor 1 shown in FIG.1 and FIG.2 is mounted from the back surface side in the center part of the lower surface of the package base 3, as shown in FIG. The peripheral portion of the lower surface of the package base 3 is in contact with the peripheral portion of the opening of the chamber 2 via an O-ring 3a to form a sealed structure. The package base 3 is fixed to the fixture 4 by a cylindrical suspension part (suspension ring) 41. The fixture 4 is fixed to a fixing portion (fixing ring) 42 of the chamber 2 using pressers 5a and 5b. The heater electrodes 15a and 15d and the sensor electrodes 15b and 15c of the sensor 1 shown in FIGS. 1 and 2 are connected to the wirings 8a, 8b, 8c, 8d, 9a and 9b, the connector 6 and the like shown in FIG. It is connected to the measurement circuit 10. A chiller unit 7 is disposed outside the lower surface side of the chamber 2. The chiller unit 7 is supplied with water at a constant temperature in order to cool the chamber 2.

  As shown in FIG. 4, the measurement circuit 10 includes an operational amplifier 101 connected to the heater 131 and a timing generation unit 100 connected to the operational amplifier 101. The timing generation unit 100 generates a drive pulse for heating the heater 131. The operational amplifier 101 receives the control signal CNT from the outside, amplifies the drive pulse from the timing generation unit 100, and transmits it to the heater 131. The heater 131 heats the semiconductor layer 13 in accordance with the drive pulse current.

  Operational amplifiers 102 and 103 and an A / D converter 104 are sequentially connected to the temperature detection element D1. The operational amplifier 102 converts a current signal or the like corresponding to the temperature of the semiconductor layer 13 detected by the temperature detection element D1 into a voltage signal. The operational amplifier 103 amplifies the voltage signal from the operational amplifier 102 to a desired level. The A / D converter 104 converts the analog voltage signal from the operational amplifier 103 into a digital signal.

  A pre-heating temperature storage unit (register) 105 and a post-heating temperature storage unit (register) 106 are connected to the output side of the A / D converter 104. A temperature difference calculation unit 107 is connected to the pre-heating temperature storage unit 105 and the post-heating temperature storage unit 106. A temperature difference storage unit 108 is connected to the temperature difference calculation unit 107, and a measurement unit 109 is connected to the temperature difference storage unit 108.

  The pre-heating temperature storage unit 105 receives a digital signal from the A / D converter 104 corresponding to the temperature of the semiconductor layer 13 before heating by the heater 131 in synchronization with the clock signal before heating from the timing generation unit 100 to the heater 131. Remember. The post-heating temperature storage unit 106 receives a digital signal from the A / D converter 104 corresponding to the temperature of the semiconductor layer 13 heated by the heater 131 in synchronization with the clock signal after heating from the timing generation unit 100 to the heater 131. Remember.

  The temperature difference calculation unit 107 reads the temperature of the semiconductor layer 13 before heating by the heater 131 stored in the pre-heating temperature storage unit 105 and the temperature of the semiconductor layer 13 after heating by the heater 131 stored in the post-heating temperature storage unit 106. Thus, the temperature difference of the semiconductor layer 13 before and after being heated by the heater 131 is calculated. The temperature difference storage unit 108 stores the temperature difference of the semiconductor layer 13 before and after heating by the heater 131 calculated by the temperature difference calculation unit 107 in synchronization with the clock signal generated from the timing generation unit 100. The measurement unit 109 reads the temperature difference of the semiconductor layer 13 before and after heating by the heater 131 stored in the temperature difference storage unit 108, and refers to the calibration curve data acquired in advance to determine the gas pressure in the chamber 2 from the temperature difference. taking measurement.

  An output unit 110 is connected to the temperature difference calculation unit 107. The output unit 110 outputs the temperature difference stored in the temperature difference storage unit 108. The output unit 110 may display the temperature of the semiconductor layer 13 before and after heating by the heater 131, the measured gas pressure in the chamber 2, and the like. As the output unit 110, a liquid crystal display, a CRT display, an inkjet printer, a laser printer, or the like can be used.

  A display unit 111 is connected to the measurement unit 109. As the display unit 111, for example, a light emitting diode (LED) can be used. The display unit 111 displays an LED so that the height of the gas pressure can be recognized according to the gas pressure measured by the measuring unit 109.

  FIG. 5A shows the timing of the drive pulse of the heater 131, and FIG. 5B shows the heat dissipation state of the heater 131 when the chamber 2 is at atmospheric pressure. At time t1 about 1 ms to 20 ms before heating by the heater 131, the temperature detection element D1 detects the temperature T11 of the semiconductor layer 13 before heating by the heater 131 as shown in FIG. The temperature T11 of the semiconductor layer 13 before being heated by the heater 131 is substantially equal to the temperature in the chamber 2.

  At time t2 to t3, as shown in FIG. 5A, a drive pulse is given to the heater 131. The drive pulse width Wp is about 1 ms to 900 ms, and the period is about 1 ms to 900 ms. In response to the drive pulse, the temperature of the heater 131 rises as shown in FIG.

  When the drive pulse is turned off at time t3 as shown in FIG. 5A, the temperature of the heater 131 decreases as shown in FIG. 5B. At time t4 when 1 ms to 50 ms have elapsed from time t3, the temperature detection element D1 detects the temperature T12 of the semiconductor layer 13 after being heated by the heater 131.

  The temperature in the chamber 2 may change due to external influences such as the temperature of water supplied to the chiller unit 7. For this reason, the measurement of the temperature T11 of the semiconductor layer 13 before heating by the heater 131 detected at time t1 means to measure the temperature as a result of being affected by the outside. The temperature T12 of the semiconductor layer 13 after being heated by the heater 131 detected at time t4 is also influenced by the outside, but it is obvious that this effect is the same as the result measured in advance at t1. Therefore, the temperature difference ΔT1 between the temperature T11 of the semiconductor layer 13 before heating by the heater 131 detected at time t1 and the temperature T12 of the semiconductor layer 13 after heating by the heater 131 detected at time t4 is the gas in the chamber 2 Depends only on the pressure of the chamber 2 and is constant without being affected even if the temperature in the chamber 2 changes. Therefore, since the temperature difference calculation unit 107 calculates the temperature difference ΔT1 and the measurement unit 109 measures the pressure of the gas in the chamber 2 from the temperature difference ΔT1, the chamber 2 can be accurately detected without being affected by the temperature in the chamber 2. The pressure of the gas inside can be measured. Furthermore, after about 1 ms to 20 ms have elapsed from time t4, the display unit 111 displays the measurement result as an LED.

  FIG. 5C shows a heat dissipation state of the heater 131 when the chamber 2 is in a reduced pressure state. Since the thermal conductivity is lower in the reduced pressure state than in the atmospheric pressure, the heater 131 releases heat gradually. As in the case of atmospheric pressure, the temperature difference between the temperature T21 of the semiconductor layer 13 before heating by the heater 131 detected at time t1 and the temperature T22 of the semiconductor layer 13 before heating by the heater 131 detected at time t4. ΔT2 depends only on the pressure of the gas in the chamber 2 and is not affected independently of the temperature in the chamber 2.

  FIG. 6 shows the temperature difference of the semiconductor layer 13 detected before and after heating by the heater 131 and the pressure of the gas in the chamber 2 when the water temperature supplied to the chiller unit is changed at 25 ° C., 35 ° C., and 45 ° C. The relationship is shown. When the water temperature of the chiller unit 7 is changed, the temperature in the chamber 2 changes. 6 that even if the temperature in the chamber 2 changes, the temperature difference of the semiconductor layer 13 before and after heating by the heater 131 is substantially constant without being affected by the temperature change in the chamber 2. It can also be seen that the temperature difference of the heater 131 is smaller as the gas pressure in the chamber 2 is higher. Therefore, the pressure of the gas in the chamber 2 is measured based on the temperature difference ΔT1, ΔT2 of the semiconductor layer 13 before and after the heating by the heater 131 with reference to the calibration curve data of the pressure of the gas in the chamber 2 acquired in advance. Can do.

  Next, the measurement method according to the embodiment of the present invention will be described with reference to the flowchart of FIG.

  (A) In step S1, the temperature detection element D1 detects the temperature of the semiconductor layer 13 whose surface is in thermal contact with the measurement target (gas) before being heated by the heater 131. The detected temperature of the semiconductor layer 13 before heating by the heater 131 is stored in the pre-heating temperature storage unit 105.

  (B) In step S2, a driving pulse is applied to the heater 131 to heat it, and the heater 131 is turned off.

  (C) In step S3, the temperature of the semiconductor layer 13 whose surface is in thermal contact with the measurement target (gas) is detected by the temperature detection element D1 in the off state after heating by the heater 131 (the off state after heating). In FIG. 5, the temperature of the semiconductor layer 13 gradually decreases as shown in FIG. The detected temperature of the semiconductor layer 13 after heating by the heater 131 is stored in the post-heating temperature storage unit 106.

  (D) In step S 4, the temperature difference calculation unit 107 uses the temperature of the semiconductor layer 13 before heating by the heater 131 stored in the pre-heating temperature storage unit 105 and the heater 131 stored in the post-heating temperature storage unit 106. The temperature of the semiconductor layer 13 after heating is read, and the temperature difference of the semiconductor layer 13 before and after heating by the heater 131 is calculated. The calculated temperature difference is stored in the temperature difference storage unit 108.

  (E) In step S5, the measurement unit 109 reads the temperature difference stored in the temperature difference storage unit 108, and converts the pressure of the gas in the chamber 2 from the temperature difference. The display unit 111 displays the measurement result as an LED.

  According to the sensor 1, the measuring apparatus using the sensor 1, and the measuring method according to the embodiment of the present invention, the pressure of the gas in the chamber 2 is accurately measured without being affected by the temperature variation in the chamber 2. can do.

  Furthermore, since the structure of the sensor 1 is simple and the size is small, the sensor 1 can be manufactured at a low cost and the yield can be improved.

(Other embodiments)
As described above, the present invention has been described according to the embodiment. However, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  In the description of the embodiment already described, the case where the semiconductor resistance region 131 serving as a heater is embedded in the surface of the semiconductor layer 13 has been described. However, the present invention is not limited to this. For example, a resistance layer made of a thin film of polycrystalline silicon or refractory metal may be deposited on the surface of the semiconductor layer 13.

  Although the diode has been described as the temperature detection element D1, a bipolar transistor may be used as the temperature detection element D1 instead of the diode, and the diode characteristics of the base and the emitter may be used. If calibration curve data for the gas type and gas flow rate in the chamber 2 is acquired in advance, the gas type and gas flow rate can be measured in addition to the gas pressure in the chamber 2.

  Further, in the above-described embodiment, the case where the pressure of the gas inside the chamber 2 is measured has been described, but the chamber is not necessarily required. For example, it can be used to measure the flow rate of gas in piping, the flow rate of air in an air conditioning duct, and the like, and the pressure of the earth's atmosphere that can be regarded as an infinite volume may be used as a measurement target.

  As described above, the present invention naturally includes various embodiments not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

It is sectional drawing which shows an example of the sensor of the measuring apparatus which concerns on embodiment of this invention. It is a top view which shows an example of the sensor of the measuring apparatus which concerns on embodiment of this invention. It is sectional drawing which shows the example of mounting of the sensor of the measuring apparatus which concerns on embodiment of this invention. It is a block diagram which shows an example of the measuring apparatus which concerns on embodiment of this invention. FIG. 5A, FIG. 5B, and FIG. 5C are graphs for explaining the measurement method according to the embodiment of the present invention. It is a graph showing the relationship between the pressure which concerns on embodiment of this invention, and the temperature difference of the semiconductor layer before and behind heater heating. It is a flowchart which shows an example of the measuring method which concerns on embodiment of this invention.

Explanation of symbols

D1 ... temperature detection element (diode)
DESCRIPTION OF SYMBOLS 1 ... Sensor 2 ... Chamber 3 ... Package base 3a ... O-ring 4 ... Fixing tool 5a, 5b ... Presser 6 ... Connector 7 ... Chiller unit 8a, 8b, 8c, 8d, 9a, 9b ... Wiring 10 ... Measurement circuit 11 ... Support Substrate 12 ... Embedded insulating film (BOX layer)
13. Semiconductor layer (SOI layer)
DESCRIPTION OF SYMBOLS 14 ... Field insulating film 15 ... Metal film 15a, 15d ... Heater electrode 15b, 15c ... Sensor electrode 16a, 16d ... Heater electrode pad 16b, 16c ... Sensor electrode pad 17 ... Air gap 100 ... Timing generation part 101, 102 , 103 ... operational amplifier 104 ... A / D converter 105 ... pre-heating temperature storage unit 106 ... post-heating temperature storage unit 107 ... temperature difference calculation unit 108 ... temperature difference storage unit 109 ... measurement unit 110 ... output unit 111 ... display unit 131 ... Semiconductor resistance area (heater)
132 ... Anode region 133 ... Cathode region

Claims (5)

A semiconductor layer whose surface is in thermal contact with the gas to be measured;
A heater for heating the semiconductor layer;
A temperature detecting element that is embedded in the upper part of the semiconductor layer and detects the temperature of the semiconductor layer before and after heating by the heater, and from the temperature difference of the semiconductor layer before and after the heating, the gas type, pressure, Alternatively, a sensor that measures flow rate.   The sensor according to claim 1, wherein the heater is embedded in the upper portion of the semiconductor layer so as to be separated from the temperature detection element. A semiconductor layer whose surface is in thermal contact with the gas to be measured, a heater for heating the semiconductor layer, and a temperature of the semiconductor layer embedded in the upper part of the semiconductor layer before and after heating by the heater A sensor having a temperature detection element;
And a measurement circuit that inputs a temperature difference between the semiconductor layers before and after the heating from the temperature detection element and calculates a gas type, pressure, or flow rate of the gas.   The measurement apparatus according to claim 3, wherein the heater is embedded in the upper portion of the semiconductor layer so as to be separated from the temperature detection element. Heating the semiconductor layer whose surface is in thermal contact with the gas to be measured by a heater;
Detecting the temperature of the semiconductor layer before and after being heated by the heater with a temperature detecting element embedded in the upper part of the semiconductor layer;
Measuring the gas type, pressure, or flow rate of the gas from the temperature difference before and after the heating.

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