KR101477144B1 - Resistive oxide for bolometer, and bolometer and IR detector using the same - Google Patents

Abstract

The present invention relates to a resistive oxide for a bolometer, and a bolometer and an infrared detecting element comprising the same. The resistive oxide for a bolometer according to the present invention comprises (Ni, Co, Mn) O ₄ system containing nickel, cobalt, And contains CuO as an additive and exhibits a negative temperature coefficient characteristic. The resistive oxide for the bolometer can exist in a stable phase in the operating temperature range with low resistivity, high TCR value, low noise characteristic, and it is possible to manufacture a bolometer and an infrared detecting device including the bolometer with excellent precision and improved temperature stability Do.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resistive oxide for a bolometer and a bolometer and an infrared detector using the resistive oxide,

The present invention relates to a resistive oxide for a bolometer and a bolometer and an infrared ray detecting element including the resistive oxide for a bolometer. More particularly, the present invention relates to a resistive oxide for a bolometer including an (Ni, Co, Mn) O ₄ system as a matrix and CuO as an additive, And a bolometer and an infrared ray detecting element including the same.

Infrared sensors are classified into Photon and Thermal. The photon type mainly uses compound semiconductors and absorbs the energy of infrared rays and uses the photoconductive phenomenon to detect excited electronic signals. The photon type is excellent in performance, but requires a liquid nitrogen cooler and has a high price. On the other hand, as a method of detecting the thermal energy to be radiated by resistance, current, or electromotive force change, performance is lower than that of the photon type, but it is generally used most because it does not need a cooler and is cheap. Thermal infrared sensors are divided into a super-type, a resistance type, and a thermoelectric type. The thermal type sensors which are mainly used now are a super-type and a resistance type.

A bolometer is a thermal resistance sensor that can detect infrared rays by measuring the change in electrical resistance due to the temperature rise when the infrared rays absorbed from the object are absorbed and converted into thermal energy. The bolometer is arranged two- Infrared images can also be implemented. The important design parameters of the bolometer are the low thermal conductivity of the bolometer and the surrounding environment, the high infrared absorption rate through the wide absorption area, the low 1 / f noise characteristic, and the sufficiently low temperature constants. In particular, Low resistance, connection with IC process, low cost and simplification of manufacturing process, and high reproducibility are required.

Currently used bolometer materials include metal thin films such as Ti, vanadium oxide, and amorphous silicon. In the case of using a metal thin film, the resistance at room temperature is very low. However, since the TCR value is very small, it is necessary to improve the responsivity of the device.

In amorphous silicon, the response characteristic is good because of the high TCR value. On the other hand, since the bolometer resistance layer made of amorphous silicon is very thin and the heat capacity is low, it is necessary to design a structure that keeps the thermal conductivity low to maintain the constant temperature. (Johnson noise) caused by the noise is high.

In addition, the vanadium oxide, which is the most widely applied material, has a relatively low TCR value of about -2.0% / ° C, which is relatively higher than that of the metal thin film. However, VO ₂ , V ₂ O ₅ , V ₂ O ₃ , and the like, and it is difficult to reproduce the phase transition from an insulator or a semiconductor to a metal phase at a specific temperature. In general, it is difficult to manufacture expensive equipments such as an ion beam device and a high- . In order to solve the problem that it is difficult to apply to a bolometer element due to a very high resistance, a method of lowering the resistance of vanadium oxide by doping vanadium oxide with another metal such as tungsten, chromium, or manganese is known as U.S. Patent No. 5,288,380. However, this method has been invented only for the purpose of lowering the resistance of vanadium oxide by doping, and has been extensively described without indicating the exact doping composition. The improvement of the TCR value, which greatly affects the performance of the infrared device due to doping, There are still many problems because the invention is not carried out.

1. U.S. Patent No. 5,288,380 (Feb. 22, 1994)

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and aims to improve the performance of a bolometer element by providing a resistive oxide which is a resistance material for a new bolometer having a low resistance and a high TCR value. It is also intended to provide a highly sensitive infrared sensing device that can operate stably at operating temperature using a new resistive oxide.

The resistive oxide for a bolometer according to an embodiment of the present invention comprises a (Ni, Co, Mn) O ₄ system containing nickel, cobalt, and manganese as main components as a matrix, CuO as an additive, (Negative Temperature Coefficient).

Further, the resistive oxide for the bolometer satisfies the following formula (1)

(Ni, Co, Mn) _{1- x} Cu _x ] O ₄ , wherein x is 0.1? X? 0.3,

The resistivity at room temperature is 200? Cm or less,

The absolute value of the resistance temperature coefficient (TCR) at room temperature is 3% / DEG C or more,

Characterized in that the matrix and the additive form a solid solution.

According to another aspect of the present invention, there is provided a bolometer comprising: a substrate; (Ni, Co, Mn) O ₄ system containing nickel, cobalt, and manganese as main components, CuO as an additive, and a negative temperature coefficient ) Resistive oxide layer; And a support member connecting and supporting the substrate and the oxide layer at all times.

And an infrared reflective layer disposed on the substrate and the resistive oxide layer and an infrared reflective layer disposed on the resistive oxide layer, wherein the infrared reflective layer may be formed on an upper surface of the substrate or a lower surface of the resistive oxide layer However,

The supporting member includes at least a pair of supporting columns extending upward from the substrate; And a support layer connected between the pair of support pillars to support the resistive oxide layer,

Wherein the resistive oxide layer satisfies the following formula (1)

(Ni, Co, Mn) _{1- x} Cu _x ] O ₄ , wherein x is 0.1? X? 0.3,

Characterized in that the resistivity at room temperature is 200? 占 cm m or less and the absolute value of the resistance temperature coefficient (TCR) at room temperature is 3% / 占 폚 or more and the resistive oxide layer forms solid solution.

Further, an infrared detecting element according to another embodiment of the present invention includes the bolometer.

The resistive oxides for the bolometer including CuO as the matrix and the (Ni, Co, Mn) O ₄ system containing nickel, cobalt and manganese as main components according to the present invention have low resistivity, high TCR value, It is possible to manufacture a bolometer and an infrared detecting device including the bolometer having excellent precision and improved temperature stability in a stable phase in the operating temperature range.

1 is a flowchart showing a method for producing a resistive oxide for a bolometer according to the present invention.
2 is a graph showing X-ray diffraction characteristics according to the composition of [(Ni, Co, Mn) _{1- x} Cu _x ] O ₄ according to the present invention.
3 is a graph showing the resistivity and TCR characteristics of [(Ni, Co, Mn) _{1 - x} Cu _x ] O ₄ according to an embodiment of the present invention.
4 is a graph showing the resistivity and TCR characteristics of [(Ni, Co, Mn) _{1 - x} Cu _x ] O ₄ according to another embodiment of the present invention.
5 is a sectional view showing a bolometer for an infrared detecting element according to another embodiment of the present invention.

The following detailed description of specific embodiments provides several explanations of specific embodiments of the invention. However, the present invention may be embodied in many different ways that are defined and covered by the claims. This description is made with reference to the drawings, wherein like reference numerals denote like or functionally similar elements.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout.

1 is a flowchart showing a method for producing a resistive oxide for a bolometer according to the present invention.

First, in order to produce a resistive oxide for a bolometer having a spinel crystal structure of AB ₂ O ₄ , Mn (Mn) constituting the (Ni, Co, Mn) O ₄ system containing nickel, cobalt and manganese ₃ O ₄ , Co ₃ O ₄ , NiO powder and CuO powder as an additive are weighed according to the molar ratio and mixed (S100). In this case, the (Ni, Co, Mn) O ₄ -based resistive oxide satisfies a composition formula of [(Ni, Co, Mn) _1-x Cu _x ] O ₄ wherein x, 0.3. The powder weighed according to the molar ratio was ball milled with ethyl alcohol or methyl alcohol as a dispersing solvent and mixed. The ratio of the dispersion solvent to the balls is 1: 1, and the balls are wet-mixed with zirconia balls for 24 hours.

Next, the mixed powder is placed in an alumina crucible and calcined by heat treatment at a temperature of 800 to 1000 ° C for 1 to 3 hours. Thereafter, the mixture is ball milled using a dispersing solvent and a zirconia ball, A compound powder is formed (S200). The calcining and pulverizing step may be repeatedly carried out a plurality of times in order to produce a stable intermediate compound. At this time, TG (differential thermal analysis) was measured for powder mixed with each starting material, and a preferable calcination temperature was determined in parallel with XRD analysis of the calcined powder. . The calcination was carried out at a temperature of 800 to 1000 ° C for 1 hour to 3 hours. However, the reaction between the raw powders was not sufficient at a temperature lower than that, and there was a disadvantage in that the subsequent procedure, which is a subsequent procedure, was difficult to carry out.

After the calcination, a small amount of a binder was added to the pulverized intermediate compound powder to uniformize the particle size to 10 μm or less, followed by applying a forming pressure of ¹ ton / cm ² to the disk-shaped specimen having a diameter of 10 mm (S300). At this time, it is preferable that 5 wt% of 10% PVA aqueous solution as a binder is added to the binder.

The formed body was heated at a rate of 1 ° C / minute for 2 hours and held at 250 ° C for 2 hours to evaporate adsorbed water (H ₂ O) and attached water (OH). At 600 ° C, (OH) and binders were volatilized. Thereafter, a sintered body having a spinel crystal structure was formed by performing a heat treatment using a platinum plate at a temperature of 1150 to 1260 ° C for 3 hours to 5 hours (S400). When the sintering temperature is lower than 1150 캜, the sintering is insufficient and the spinel crystallinity is not sufficient. When the sintering temperature is higher than 1250 캜, the grain size becomes too large and some regions are melted and abnormal growth may occur.

After the sintered body was polished and cleaned, silver paste was screen-printed on both sides, dried in a 100 ° C dry oven, and then baked at 600 ° C for 10 minutes to form electrodes. .

The manufacturing process of the resistive oxide for a bolometer according to the present invention is not limited to the above, and various modifications and changes can be made depending on the characteristics of the desired device and the convenience of the process.

2 is a graph showing X-ray diffraction characteristics according to the composition of [(Ni, Co, Mn) _{1- x} Cu _x ] O ₄ according to the present invention. This is to grasp the crystal structure by changing the angle on the surface of the resistive oxide to be analyzed and irradiating a specific X-ray beam and reading the intensity of the X-ray beam diffracted according to the characteristics of the crystal plane. As shown in Fig. 2, in which only the main XRD peaks found in the spinel crystal structure are observed, in all the specimens to which CuO was added at (Ni, Co, Mn) O ₄ base material and various molar ratios (x) And it can be confirmed that the compound of the single-phase spinel structure is synthesized well as a solid solution state. These compounds remain stable until their melting point. That is, in the case of vanadium oxide which is conventionally used as a bolometer resistor, there are numerous intermediate phases such as VO2, V2O5 and V2O3, and it is difficult to produce a reproducible bolometer. In contrast, [(Ni, Co, Mn) _1-x Cu _x ] O ₄ oxide is stably present over a wide temperature range, so that the bolometer and the infrared detecting device manufactured using the same can have improved temperature stability.

Theoretical densities were calculated from the lattice constants obtained by XRD analysis of the sintered specimens, and the relative density was compared with the sintered density obtained by the Archimedes' method. The relative density of [(Ni, Co, Mn) _{1 - x} Cu _x ] O ₄ oxides was found to be over 95% with respect to all CuO additions, and the relative density did not show any particular change with the addition of CuO.

3 to 4 are graphs showing the resistivity and TCR characteristics of [(Ni, Co, Mn) _1-x Cu _x ] O ₄ according to the embodiment of the present invention in which the composition ratios of Ni, CO and Mn are different.

In the case of FIG. 3 _{[(Ni 0 .3 Co 0 .33} Mn 0 .37) 1- x Cu x] O 4 as a result of the resistive oxide, is compared with the case where the specific resistance at room temperature is not added CuO CuO It is understood that the amount thereof is sharply decreased with the addition of the catalyst.

Having a spinel structure of AB ₂ O ₄ composition (Ni, Co, Mn) O 4 system the Ni ^{2 +} occupies tetrahedral site (A-site), Mn 3 + and Co ^{3 +} the octahedral site (B-site ). Electrical conduction to such a spinnel structure is achieved by electron hopping between Mn ^{3 +} and Mn ^{4 +} located at the B-site. On the other hand, in the case of an inverted spinnel structure, both Ni and Mn ions can occupy tetrahedral sites and octahedral sites. Ni ^{2 +} present in the octahedral site induces the valence change from Mn ^{3 +} to Mn ^{4 +} . When CuO is (Ni, Co, Mn) O is added to the _four-based Cu ^{2 +} ions are Ni ^{2 +} a there is preferentially substituted, Cu ^{2 +} ions of the Mn ion valence change than heavy Ni ²⁺ ions than Ni ^{2 +} (Ni, Co, Mn) O ₄ system, the resistivity decreases as CuO is added to the (Ni, Co, Mn) O ₄ system, which causes more electrons hopping between Mn ^{3 +} and Mn ^{4 +} will be. On the other hand, (Ni, Co, Mn) O when CuO is added too much, the _four series is by the Jahn Teller effect of (Ni, Co, Mn) O 4 system Mn ^{3 +} ions due to the instability of the twisting of the MnO ₆ octahedral , Which makes it difficult to hop electrons between Mn ^{3 +} and Mn ^{4 +} , so that the resistivity is no longer lowered by the addition of CuO.

 The resistance of the resistor for a bolometer that changes its resistance value in accordance with the temperature change due to infrared absorption is required to have a low resistance value because the noise of the bolometer increases as the resistance increases. The operating temperature of the infrared detecting device including the bolometer is generally At room temperature to 50 ° C. The resistivity of the resistor for a bolometer is required to be 200 Ω · cm or less in this temperature range. On the other hand, in recent years, miniaturization of an infrared detecting element has necessitated a microbolometer. For this purpose, a resistivity of 100 Ω · cm or less is required.

On the other hand, as CuO is added to the (Ni, Co, Mn) O ₄ system, the resistivity decreases and the absolute value of the TCR, which is another important property of the IR detector element, is also decreased. The absolute value of TCR at room temperature was 5.18% / ° C for CuO-free (Ni, Co, Mn) O ₄ oxides but the absolute value of TCR at room temperature was 3.67% / [Deg.] C. When the composition ratio (x) of Cu is 0.30 or less, the absolute value of the room temperature TCR is maintained at 3% / ° C in the operating temperature range of the infrared detecting element. If x exceeds 0.3, the absolute value of the room temperature TCR is 3% Lt; / RTI >

4 [(Ni Co _{0 .263 0 .131 0 .605} Mn) _{1- x} Cu _x] O ₄ indicate the resistivity and TCR change in the resistive oxide, similar to the added amount of CuO increased as we have seen thus as a specific resistance And the absolute value of TCR decrease. That is, when CuO is not added, it shows a very high specific resistance value at room temperature, but it becomes rapidly lower as CuO is added, so that it can be used as a bolometer applied to an infrared detecting element. The TCR at room temperature also decreases with the addition of CuO, but it maintains more than 3% / ℃ even when the amount of CuO added (x) is 0.30.

Therefore, in the resistive oxide for a bolometer according to the present invention, the composition ratio x of CuO added to the (Ni, Co, Mn) O ₄ matrix can be selected within the range of 0.1 to 0.3 ([(Ni, Mn) _{1- x} Cu _x ] O ₄ , wherein x is 0.1? X? 0.3.

5 is a sectional view showing a bolometer for an infrared detecting element according to another embodiment of the present invention. A bolometer for an infrared detecting element according to the present invention includes a substrate 510; (Ni, Co, Mn) O ₄ system containing nickel, cobalt, and manganese as main components, CuO as an additive, and a negative temperature coefficient ) Resistive oxide layer (530); And a support member 520 for supporting and supporting the substrate and the oxide layer all the time.

The substrate 510 is a semiconductor substrate including an infrared detection circuit therein, and is made of a semiconductor material such as silicon.

The resistive oxide layer 530 is a resistor for a bolometer that changes its resistance by absorbing infrared rays and accordingly changes its resistance. The resistive oxide layer 530 is spaced apart from the substrate 510 and includes nickel, cobalt, and manganese , Co, Mn) O ₄ system as a matrix, CuO as an additive, and a negative temperature coefficient characteristic. The composition of this resistive oxide layer can be expressed by the following formula (1).

≪ Formula 1 >

[(Ni, Co, Mn) _{1 - x} Cu _x ] O ₄ , wherein x is 0.1? X? 0.3.

The resistive oxide layer may have a resistivity at room temperature of 200? Cm or less and an absolute value of the resistance temperature coefficient (TCR) at room temperature of 3% / 占 폚 or higher in order to improve infrared sensitivity and temperature stability of the bolometer.

The support member 520 connects and supports the substrate 510 and the resistive oxide layer 530. The resistive oxide layer 530 and the resistive oxide layer 530 are formed on the substrate 510 to minimize thermal conduction between the resistive oxide layer 530 and the surroundings. 530 are separated from each other by the spacing space 560 without being in contact with each other. The support member 520 includes at least a pair of support pillars 521 extending upward from the substrate and a support layer connected between the pair of support pillars 521 to support the resistive oxide layer 530 522). The support pillars 521 may be made of a material having a low thermal conductivity and formed to have a small cross-sectional area in order to minimize thermal conduction to the surroundings while having a mechanical strength to support the resistive oxide layer. The support layer 522 must be in direct contact with the resistive oxide layer disposed thereon and should not react with the upper resistive oxide layer and have insulating properties. For example, a silicon oxide film, an aluminum oxide film, a titanium oxide film, or the like.

Meanwhile, an infrared ray reflective layer 540 may be disposed between the substrate 510 and the resistive oxide layer 530. In order to increase the infrared absorption rate in the resistive oxide layer for the bolometer, an optical resonance structure optimized for the target infrared wavelength band is required. For this purpose, a reflection layer 540 is formed on the substrate, and a resistive oxide layer is formed on the surface of the infrared reflection layer So that most of infrared rays incident at a wavelength of? Can be absorbed in the resistive oxide layer. In addition to resonating using the spacing between the infrared reflecting layer and the resistive oxide layer, the resistive oxide layer itself may be formed in a resonant structure. This is because there is a reflective layer in contact with the bottom of the resistive oxide layer, / 4. ≪ / RTI > The infrared reflecting layer 540 may be a dispersion brazing reflective layer formed by alternately laminating metal layers such as gold or silver or dielectric layers having different refractive indices (for example, alternating layers of SiO ₂ and TiO ₂ ) as known to those skilled in the art Lt; / RTI >

In addition, the infrared ray reflection layer 550 may further include an infrared ray reflection preventing layer 550 on the resistive oxide layer 530 so that the infrared ray incident toward the bolometer can be absorbed by the inner resistive oxide 530 without being reflected back to the outside. The infrared reflection preventing layer 550 can be formed by laminating a single layer or a plurality of layers of an oxide of a metal such as zinc, tin, aluminum, titanium, or silicon, which can be easily selected by those skilled in the art.

As described above, according to the present invention, by adding CuO to the matrix of (Ni, Co, Mn) O ₄ system containing nickel, cobalt and manganese as main components, vanadium oxide It is possible to obtain a resistive oxide having a low resistivity, a high TCR value and a low noise characteristic as well as a stable phase in a wide temperature range and having excellent precision and improved temperature stability, compared with amorphous silicon and the like. In addition, when the resistive oxide according to the present invention is used as a resistor for a bourometer, it becomes possible to manufacture a bolometer and an infrared ray detecting element having excellent infrared ray detecting characteristics.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but many variations and modifications may be made without departing from the spirit and scope of the invention. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the present invention. Accordingly, the technical scope of the present invention should be defined by the following claims.

510: substrate 520: support member
521: Support column 522: Support layer
530: a resistive oxide layer 540: an infrared reflective layer
550: Infrared reflection preventive layer

Claims (15)

delete delete delete delete delete Board;
(Ni, Co, Mn) O ₄ system containing nickel, cobalt, and manganese as main components, CuO as an additive, and a negative temperature coefficient ) Resistive oxide layer;
A support member connecting and supporting the substrate and the oxide layer at all times; And
And an infrared reflecting layer disposed between the substrate and the resistive oxide layer.
delete The method according to claim 6,
And an infrared anti-reflection layer disposed on the resistive oxide layer.
The method according to claim 6,
Wherein the support member comprises:
At least a pair of support columns extending upward from the substrate; And
And a support layer connected between the pair of support pillars to support the resistive oxide layer.
The method according to claim 6,
Wherein the infrared reflecting layer is formed on the upper surface of the substrate or the lower surface of the resistive oxide layer.
The method according to claim 6,
Wherein the resistive oxide layer satisfies the following formula (1).
≪ Formula 1 >
[(Ni, Co, Mn) _{1 - x} Cu _x ] O ₄ , wherein x is 0.1? X? 0.3.
The method according to claim 6,
And the resistivity of the resistive oxide layer at room temperature is 200? Cm or less.
12. The method of claim 11,
Wherein an absolute value of a resistance temperature coefficient (TCR) of the resistive oxide layer at room temperature is 3% / DEG C or more.
The method according to claim 6,
Wherein the resistive oxide layer forms a solid solution.
An infrared ray detecting element comprising the bolometer of any one of claims 6, 8,

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