KR100612203B1 - Temperature sensor - Google Patents

Abstract

A first resistance layer provided on the substrate and having a predetermined temperature coefficient (TCR) to maintain a constant resistance value against temperature change; Disclosed is a resistive temperature sensor comprising: a second resistive layer connected in series with a first resistive layer, the second resistive layer having a temperature coefficient (TCR) which is varied to change a resistance value in response to a temperature change.

Temperature sensor, resistance, polysilicon, temperature coefficient

Description

Temperature sensor {Temperature sensor}

1 is a view showing a temperature sensor according to an embodiment of the present invention,

2 is an equivalent circuit diagram illustrating the temperature sensor shown in FIG. 1;

3a to 3f are views for explaining the manufacturing method of the temperature sensor shown in FIG.

<Description of Symbols for Main Parts of Drawings>

10. Substrate 20. Insulation layer

30. Temperature sensor 40. Polysilicon layer

41 .. First resistive layer 43. Second resistive layer

45. Electrode pads 51, 52, 53. First, second and second electrode terminals

] 60. Voltage supply part 70. Voltage measurement part

80..First protective film 90..Second protective film

The present invention relates to a temperature sensor, and more particularly to a temperature sensor applicable to the MEMS (Micro Electro Mechanical System).

MEMS technology is a technology that implements mechanical parts into electrical devices using semiconductor processes.In this way, it is possible to design machines and equipment with ultra-fine structures of several micrometers or less. It is expected to revolutionize the entire industry. In particular, the sensors manufactured by the MEMS technology, which has recently been in the spotlight, are generally manufactured in a very small size, and thus are provided in various small devices such as a mobile phone to sense and provide various information.

On the other hand, temperature sensors are used in various ways throughout the industry. For example, it is not only used for temperature control in home appliances such as air conditioners and refrigerators, but is also essential for precise production of products in precision industries such as the semiconductor industry.

The thermometers currently used are classified according to the measurement principle as follows.

First, there is a thermometer using thermal expansion. These include gas thermometers, liquid thermometers, and bimetal thermometers. Among them, the liquid thermometer includes a thermometer using mercury or kerosene. Most of the red thermometers used to be alcohol thermometers have used alcohol thermometers (using alcohol with red paint), but kerosene has been used since 30 years since condensation in the upper part of the liquor can easily occur, causing errors. Household thermometers and thermometers are one of these liquid thermometers. In addition, there is a minimum temperature thermometer and Beckman thermometer using this liquid thermometer. The bimetal thermometer uses a bimetal in which two kinds of metal plates having different thermal expansion coefficients, that is, two sheets of copper and nickel are in close contact with each other. In this bimetal thermometer, the expansion coefficient of copper is larger than that of nickel, so the temperature is displayed using the principle of bending toward the nickel plate at high temperature and bending toward the copper plate at low temperature.

Next, there is a thermal resistance thermometer using the temperature change of the electrical resistance. This includes a resistance thermometer, which uses a temperature dependence of the electrical resistance of metals and semiconductors.

Thermocouple thermometers make loops of electricity flow by touching two different metal or alloy wires at both ends. Given the difference in temperature at both ends, the thermoelectric power is generated at both ends and current flows. This is called the Peltier effect (thermoelectric effect), and the application of this is a thermocouple thermometer. The measured thermoelectric power is measured with a potentiometer or a millivolt meter with large internal resistance and is most widely used for thermometers in temperature-thermal power calibration. The reason for this is that the volume of the metal joint, which is a moisture sensitive part, is very small, so that the error according to the heat capacity is small and the response to heat is excellent. As a passion pair used, a platinum wire, a platinum rhodium alloy wire, a copper wire, a constantan wire, etc. are mentioned.

And there is a color thermometer according to the light. These include optical pyrometers and radiation pyrometers. Advertising thermometer is obtained by comparing the color temperature of the object with the standard color temperature, and can measure up to 700 ~ 2500 ℃. Radiation pyrometers collect the thermal energy radiated from the object under measurement with a lens or concave mirror and place a thermistor (a resistor sensitive to ambient temperature) at the focal point and measure the temperature based on the change in the resistance of the thermistor as the temperature increases. As one of the radiation pyrometers, there is a thermometer for thermography using a semiconductor thermosensitive element for infrared rays. Use this to investigate the surface temperature distribution of the earth or the skin temperature distribution of the human body in satellites.

There are also other zegercon and thermo color thermometers. Zegeron thermometer is a serious pyramid of about 10cm in height made of silicate and metal oxide. It is used to examine the temperature distribution in the furnace by placing it in various places in the furnace and heating it to see how the triangular pyramid melts. A thermo color thermometer is a thermometer that uses the principle that the color of a thermo color, also called a visual material, changes color. It is a thermometer using the phenomenon that cobalt, chromium, and other complex salts reversibly change color with temperature, and the material is dried with clay and is called thermocle. Recently, liquid crystal thermometers using the temperature characteristics of liquid crystals have also emerged as thermo color thermometers.

Among the thermometers according to various measurement principles as described above, the thermal resistance temperature measurement method uses the point that the electrical resistance of the conductor changes with the change of temperature. In other words, if the change rate of resistance to unit temperature change is known, the corresponding temperature can be measured using only the variable resistance value. Here, the rate of change of resistance with respect to the unit temperature is called a temperature coefficient of resistance (TCR), and when the resistance increases with increasing temperature, it is called a positive temperature coefficient (positive TCR), and when the resistance decreases, a negative temperature coefficient (negative TCR) It is called.

Metal materials mainly used for temperature measurement have positive temperature coefficients. Among them, platinum, nickel, and copper are mainly used for temperature measurement.

In the MEMS technology, polysilicon is mainly used as a material of a heat resistant temperature sensor.

In the case of polysilicon, a voltage is applied at both ends, and the polysilicon acts as a resistor, and thus the measured current value varies according to the temperature change. Therefore, the temperature can be measured by measuring the current measured corresponding to the applied voltage.

Such polysilicon has the following two TCR characteristics. That is, according to Intragrain Resistance, which represents the resistance value due to doping, the positive temperature coefficient (positive TCR) increases as the temperature increases and the phonon scattering between the silicon lattice increases. .

In addition, the grain boundary resistance, which represents a resistance value to a barrier between grain boundaries, has a negative temperature coefficient (Negative TCR) in which the resistance value decreases as the temperature increases.

Accordingly, in the case of polysilicon, the TCR value and the sheet resistance value can be controlled by appropriately controlling the doping concentration and the grain size. When using a resistive type temperature sensor as described above, it is widely used in MEMS technology because it is excellent in temperature measurement sensitivity and accuracy, but since the resistive temperature sensor consumes a lot of power, it is used in wireless devices, mobile devices, etc. There are many problems to apply.

In addition, since the operation of measuring the output current value and changing the measured current into a voltage is necessary, it has a complicated configuration.

The present invention has been made to solve the above problems, an object of the present invention to provide a temperature sensor that can measure the temperature without consuming a lot of power.

The temperature sensor of the present invention for achieving the above object is provided on the substrate, the first resistance layer having a temperature coefficient (TCR) of the change rate of the resistance value according to the temperature change is minute; And a second resistance layer connected in series with the first resistance layer and having a temperature coefficient (TCR) having a large rate of change in resistance value according to temperature change compared to the first resistance layer.

Here, first and second electrode terminals provided at both ends of the first resistance layer; It is preferable to further include a; third electrode terminal provided at one end of the second resistance layer.

In addition, the first resistance layer may have a larger base resistance than the second resistance layer.

In addition, the first resistance layer and the second resistance layer is preferably formed through a different number of doping process.

In addition, the temperature sensor manufacturing method of the present invention for achieving the above object, forming an insulating layer on the substrate; Depositing polysilicon on the insulating layer and then first doping with a predetermined material over the entire surface; And second doping a predetermined region of the first doped polysilicon layer; And forming a first and a second resistance layer by patterning the partial region of the first doped portion and the second doped region to remain. And forming electrode terminals on the first and second resistance layers.

The second doping step may include exposing a first passivation layer on the first doped polysilicon layer and then patterning and removing a portion corresponding to the first resistance layer of the first passivation layer; And doping the exposed polysilicon layer.

The forming of the first and second resistive layers may include depositing a second passivation layer over the entire surface of the first passivation layer and the exposed polysilicon; Exposing the substrate by patterning a predetermined region of the second passivation layer except for portions covering the upper portions of the first and first resistance layers; And exposing the first and second resistive layers by removing the first and second passivation layers.

The electrode terminal forming step may include depositing a metal material on the first and second resistance layers and the exposed insulating layer; And patterning the deposited metal material to provide electrode terminals in partial regions of the first and second resistance layers.

Hereinafter, with reference to the drawings will be described the present invention in more detail.

1 is a schematic view showing a resistance temperature sensor according to an embodiment of the present invention.

Referring to FIG. 1, an insulating layer 20 is deposited on a substrate 10. The temperature sensor 30 is formed on the insulating layer 20. The temperature sensor 30 includes a first resistive layer 41 and a second resistive layer 43, and the resistive layers 41 and 43 are integrally formed as a single polysilicon layer 40. That is, each of the first and second resistance layers 41 and 43 is formed of a polysilicon material, and is formed on the insulating layer 20 to have the same thickness so as to be connected in series with each other. The first resistance layer 41 has a temperature coefficient TCR whose resistance value changes minutely, that is, the resistance value hardly changes as the temperature changes. In addition, the second resistance layer 43 has a large resistance value according to the temperature change, but has a temperature coefficient (TCR) having a change rate of the resistance value relatively larger than the first resistance layer 41. For example, the degree of change in the resistance value on the basis of when the temperature changes by 1 degree may be set so that the second resistance layer 43 is tens or hundreds of times larger than the first resistance layer 41. In this case, the size of the resistance value changes at a very small rate compared to the second resistance layer 43 in the first resistance layer 41, and such a change rate can be regarded as being within an error range. Therefore, when the first resistance layer 41 is substantially set as a relative reference to the second resistance layer 43, it can be regarded that the resistance value does not change with temperature change. As described above, in order to have each of the resistance layers 41 and 43 have different temperature coefficients, a predetermined doping additive is applied to the polysilicon layer 40 through a primary or secondary doping process. Each can be doped differently. In the present embodiment, the first resistive layer 41 is formed by secondary doping, and the second resistive layer 43 is formed by primary doping. In other words, the more additives, the smaller the temperature coefficient of change in the resistance value against temperature change.

In addition, the polysilicon layer 40 has an electrode pad layer 45 connected to the second resistance layer 43. Like the first resistive layer 41, the electrode pad layer 45 may be secondly doped to have a predetermined temperature coefficient, preferably the same temperature coefficient as the first resistive layer 41.

In addition, first and second electrode terminals 51 and 52 are provided on both ends of the first resistance layer 41. In addition, a third electrode terminal 53 is formed on the electrode pad layer 45.

The first and second resistance layers 41 and 43 are connected in series with each other, as shown in FIG. 2. Each of the resistor layers 41 and 43 is connected to each other so that a voltage having a predetermined magnitude is applied from the voltage supply unit 60 through the electrode terminals 51 and 53.

Therefore, when voltage is applied from the voltage supply unit 60 to each of the resistance layers 41 and 42, the voltage across the electrode terminals 51 and 52 is measured by the voltage measuring unit 70. Therefore, the variable voltage value can be calculated. That is, since the second resistance layer 43 has a resistance value that varies at a large rate according to temperature, the voltage value applied to the second resistance layer 43 is changed, and the second resistance layer 41 has a second resistance value. Compared to the resistance layer 43, the resistance hardly changes. Accordingly, the amount of change in voltage is detected in the second resistor layer 43 from the amount of change in voltage across the first resistor layer 41, and the resistance change value of the second resistor layer 43 is calculated based on the detected voltage. can do. Then, the temperature can be calculated from the changed resistance value.

Here, by forming the basic resistance value of the first resistance layer 41 to be larger than the second resistance layer 43, even if a small voltage is applied from the voltage supply unit 60, the first resistance layer 41 is basically Since a large output value can be obtained, the change amount according to the temperature change of the second resistance layer 43 can be accurately measured. Therefore, power consumption for driving the temperature sensor can be reduced.

The temperature coefficient TCR of the second resistance layer 43 may be formed by appropriately selecting a predetermined doping additive to have a negative value or a positive value.

It looks at the temperature sensor manufacturing method according to an embodiment of the present invention having the above configuration.

First, as shown in FIG. 3A, the insulating layer 20 is deposited on the upper surface of the silicon substrate 10. After depositing the insulating layer 20, as shown in FIG. 3B, a polysilicon material is deposited on the entire upper surface of the insulating layer 20 to form a polysilicon layer 40. Then, the entire polysilicon layer 40 is first doped with a predetermined doping additive.

Next, as shown in FIG. 3C, the first passivation layer 80 is deposited on the first doped polysilicon layer 40, and then patterned to expose the polysilicon layer 40 in a predetermined region.

Next, as shown in FIG. 3C, the exposed polysilicon layer 40 and the first passivation layer 80 are secondly doped with a predetermined doping material.

Then, as illustrated in FIG. 3D, the second passivation layer 90 is deposited over the second doped portion of the polysilicon layer 40 and the entire first passivation layer 80, and then patterned to remove a partial region. . At this time, the polysilicon layer 40 and the second passivation layer 80 are also removed except for some regions.

In this state, as shown in FIG. 3E, the first and second passivation layers 80 and 90 are simultaneously removed to expose the polysilicon layer 40. The exposed polysilicon layer 40 includes first and second resistance layers 41 and 43 and an electrode pad layer 45.

Next, as illustrated in FIG. 3F, a metal material is deposited over the entire upper surface of the exposed polysilicon layer 40 and the insulating layer 20, and then patterned to only a partial region of the polysilicon 40. Leave metal material. Then, as shown in FIG. 1, the first to third electrode terminals 51, 52, and 53 are formed in a predetermined region on the polysilicon layer 40.

On the other hand, during the manufacturing process as described above, in the process of doping the polysilicon layer 40 first and second, as a doping additive, various doping additives generally known in the industry can be used.

In addition, the first doped second resistive layer 43 is manufactured so that the resistance thereof changes significantly according to the temperature change, while the second doped first resistive layer 1 is preferably changed according to the temperature change. The resistance value is hardly changed or manufactured so that it changes minutely within the error range.

Until now, a resistance temperature sensor using a polysilicon material whose resistance value changes with temperature change has been proposed, and specific examples thereof have been illustrated and described. This resistance type temperature sensor can be applied to MEMS (Micro Electro Mechanical System), and excellent effect can be obtained when applied.

As described above, the resistance type temperature sensor according to the present invention is not only excellent in temperature measurement sensitivity and accuracy, but also minimizes power consumption.

In addition, this resistance type temperature sensor is easy to calibrate and manufacture because no driving body is used.

Claims (8)

A first resistance layer provided on the substrate and having a temperature coefficient (TCR) having a small rate of change in resistance according to temperature change; And a second resistance layer connected in series with the first resistance layer, the second resistance layer having a temperature coefficient (TCR) having a larger rate of change of resistance value according to temperature change than the first resistance layer. The method of claim 1, First and second electrode terminals provided at both ends of the first resistance layer; And a third electrode terminal provided at one end of the second resistance layer. The method according to claim 1 or 2, The first resistance layer has a resistive temperature sensor, characterized in that the basic resistance value is larger than the second resistance layer. The method according to claim 1 or 2, The first resistance layer and the second resistance layer is a resistive temperature sensor, characterized in that formed through a different number of doping process. Forming an insulating layer on the substrate; Depositing polysilicon on the insulating layer and then first doping with a predetermined material over the entire surface; And Second doping a predetermined region of the first doped polysilicon layer; And Patterning a portion of the first doped portion and the second doped region to form first and second resistive layers; And And forming electrode terminals on the first and second resistance layers. The method of claim 5, wherein the second doping step, Depositing a first passivation layer on the first doped polysilicon layer and then patterning and removing a portion corresponding to the first resistance layer of the first passivation layer to expose the first passivation layer; And Doping the exposed polysilicon layer; temperature sensor manufacturing method comprising a. The method of claim 6, wherein the first and second resistance layer forming step, Depositing a second passivation layer over the entire surface of the first passivation layer and the exposed polysilicon; Exposing the substrate by patterning a predetermined region of the second passivation layer except for portions covering the upper portions of the first and first resistance layers; And Exposing the first and second resistive layers by removing the first and second passivation layers. The method according to any one of claims 5 to 7, The electrode terminal forming step, Depositing a metal material on the first and second resistive layers and the exposed insulating layer; And And patterning the deposited metal material to provide electrode terminals in partial regions of the first and second resistive layers.

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