KR101832408B1 - Resistive oxide thin film for bolometer and Method for manufacturing therof - Google Patents

Abstract

According to the present invention, a resistive oxide thin film for a bolometer comprises an oxide layer of a cubic spinel crystalline structure provided onto a substrate. The oxide layer comprises a (Ni, Mn, Cu)_3O_4 based mother object including nickel, manganese, and copper; and an addition agent added to the mother object wherein the addition agent is an element of which an atom maintains a state even when a temperature is changed. Therefore, the resistive oxide thin film for a bolometer has a high resistive temperature coefficient at high temperature as well as room temperature.

Description

Technical Field [0001] The present invention relates to a thin film for a bolometer,

The present invention relates to an oxide thin film for a bolometer and a method of manufacturing the same, and more particularly, to an oxide thin film for a bolometer capable of having a high resistance temperature coefficient at a high temperature and a method for manufacturing the same.

The temperature coefficient of resistance (TCR) of a thin film of a bolometer used as a sensing material in a bolometer, which is an infrared sensor that senses the change of infrared rays by using a thin film for a sensing material in which the resistance changes according to the temperature change due to the absorption of infrared rays, (1 / f Noise) of the resistance in the resistivity and the low frequency band. The higher the absolute value of the resistance temperature coefficient, which is the rate at which the resistance changes with the temperature change, the better the performance of the bolometer have. In addition, the thin film of the bolometer that affects the sensitivity of the bolometer has a large resistance temperature coefficient, and the smaller the specific resistance and the 1 / f noise, the better the sensing material.

In addition, the thin film of the bolometer should be compatible with the complementary metal oxide semiconductor (CMOS) process for manufacturing a readout integrated circuit (ROIC), so that it can be manufactured at low cost. Also, the bubble problem of organic sacrificial layer and ROIC In order to prevent damage to the circuit, it is necessary to satisfy the heat treatment temperature of about 400 ℃ or less.

As described above, it is known that the resistivity, which is one of the characteristics of the thin film of the bolometer, is influenced by the intrinsic factors of the electron hopping and the external factors such as the grain size and the microstructure. However, studies on the factors affecting the resistance temperature coefficient are insufficient Recently, the importance of resistance temperature coefficient at high temperature has been emphasized for developing high sensitivity infrared sensor.

Infrared sensors used in automotive night vision and Advanced Driver Assistance Systems (ADAS) are exposed to high temperature environment by environmental or device heating. Therefore, high sensitivity is required not only at room temperature but also at high temperature And thus an infrared sensor having a high resistance temperature coefficient in various temperature ranges is required.

However, vanadium oxide (VO _x ), which is widely used for the thin film of the bolometer, has a resistance temperature coefficient of about -2% / K at room temperature, and a resistance temperature coefficient of about -1% / K at high temperature, It is difficult to obtain reproducibility because it undergoes a state change from an insulator or a semiconductor to a metal state at a certain temperature. Therefore, a sophisticated process is required. In addition, in order to deposit a stable film, expensive special equipment such as a sputtering apparatus, .

Therefore, there is a demand for an oxide thin film for a bolometer capable of producing a bolometer thin film having a high resistance temperature coefficient at a high temperature as well as a room temperature, and at the same time having a suitable specific resistance at a low heat treatment temperature.

US 6489613 B

The present invention provides an oxide thin film for a bolometer capable of having a high resistance temperature coefficient at a low heat treatment temperature as well as at a high temperature by adding an additive, and a method of manufacturing the oxide thin film.

The oxide resistive thin film for a bolometer according to an embodiment of the present invention includes an oxide layer of a cubic spinel crystal structure provided on a substrate, and the oxide layer is composed of (Ni, Mn , Cu) ₃ O ₄ family matrix; And an additive which is added to the matrix and is an element that maintains a valence state even when the temperature changes.

The additive may be added in an amount of 8 wt% to 12 wt% based on the total weight of the matrix.

The additive is substituted with manganese which is located at the octahedral site of the cubic spinel crystal structure, and the bonding valence of the additive may be smaller than the bonding valence of the manganese.

The additive may include an element of at least one of boron, zinc, gallium, indium, magnesium, scandium and beryllium.

The absolute values of the room temperature resistance temperature coefficient and the high temperature resistance temperature coefficient of the oxide resistive thin film may be 1.95% / K or more, respectively.

And an oxide seed layer made of an oxide of at least one of nickel, manganese, and copper between the substrate and the oxide layer.

The method for producing an oxide thin film for a bolometer according to another embodiment of the present invention includes dissolving each of a plurality of metal oxide organic compounds and an additive that maintains a valence state even when the temperature changes, into a first organic solvent to prepare a plurality of pre- Preparing a solution; Preparing a mixed solution by mixing the plurality of pre-precursor solutions and the additive solution; Diluting the mixed solution with a second organic solvent different from the first organic solvent to prepare a precursor solution; Forming a precursor layer on the substrate by a liquid phase process using the precursor solution; And a step of converting the precursor layer into an oxide layer by performing a subsequent heat treatment in an oxidizing atmosphere.

Wherein the oxide layer comprises a (Ni, Mn, Cu) ₃ O ₄ based matrix and an additive added to the matrix, the additive being an element that maintains a valence state even when the temperature changes, To 8 wt% to 12 wt%.

The plurality of metal oxides include nickel oxide, manganese oxide, and copper oxide, and the bonding valence of the additive may be smaller than that of the manganese.

The additive may include an element of at least one of boron, zinc, gallium, indium, magnesium, cesium and beryllium.

The first organic solvent may be an aromatic hydrocarbon-based organic solvent.

The second organic solvent may be acetic ester-based organic solvent.

The subsequent heat treatment may be performed at a temperature ranging from 300 ° C to 400 ° C.

The method may further include forming a metal layer including at least one of the plurality of metal oxides on the substrate before forming the precursor layer.

The metal layer may be formed by physical vapor deposition.

The method may further include a step of preheating the metal layer at a temperature lower than the temperature of the next heat treatment to form the oxide seed layer before forming the metal layer and forming the precursor layer.

In the present invention, even when the temperature of the (Ni, Mn, Cu) ₃ O ₄ base matrix containing nickel, manganese, and copper is changed as an additive, an element which retains the valence state is added, Can have a resistivity applicable to microbolometer applications while having a high resistance temperature coefficient even at a high temperature of 占 0 C to 120 占 폚. Accordingly, it is possible to manufacture a highly sensitive infrared sensor having excellent accuracy and improved temperature stability in various environments without being limited to the temperature inside the vehicle having a high temperature by environmental or device heating. Further, the heat treatment temperature for the crystallization of the thin film can be reduced through the additive of the present invention.

In addition, since the oxide seed layer serving as a crystal nucleus is formed between the substrate and the oxide layer to induce crystal growth of the oxide layer, the heat treatment temperature required for crystal growth can be further reduced, so that an oxide thin film having a cubic spinel crystal structure Can be formed at a low heat treatment temperature range of 300 ° C to 400 ° C, and it is possible to prevent the damage of the signal processing circuit and bubbling problem of the organic sacrifice layer which occurred at a high heat treatment temperature.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view showing an oxide thin film for a bolometer according to an embodiment of the present invention; FIG.
Figure 2 is a graph and table showing the sheet resistance and TCR versus temperature according to an embodiment of the present invention.
3 is a flow chart showing a method of manufacturing an oxide-resistive thin film according to another embodiment of the present invention.
4 is a sectional view showing the structure of a spin coater according to another embodiment of the present invention.
5 is a sectional view showing a manufacturing process of a bolometer according to still another embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. It will be apparent to those skilled in the art that the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, It is provided to let you know. To illustrate the invention in detail, the drawings may be exaggerated and the same reference numbers refer to the same elements in the figures.

FIG. 1 is a cross-sectional view illustrating an oxide thin film for a bolometer according to an embodiment of the present invention, and FIG. 2 is a graph and a table showing a sheet resistance and a TCR according to an embodiment of the present invention.

1 and 2, an oxide thin film for a bolometer according to an embodiment of the present invention includes an oxide layer 120 having a cubic spinel crystal structure provided on a substrate 110, The layer 120 may be a (Ni, Mn, Cu) ₃ O ₄ based matrix containing nickel, manganese and copper; And an additive which is added to the matrix and is an element that maintains a valence state even when the temperature changes. The additive may include at least one of boron, zinc, gallium, indium, magnesium, scandium, and beryllium.

First, even when the temperature changes as an additive in the (Ni, Mn, Cu) ₃ O ₄ matrix, by adding an element that maintains a valence state, the oxide thin film for a bolometer can have a high TCR. ) Is inversely proportional to the absolute value of TCR. Therefore, for a bolometer having a good performance such as a small temperature resolution and an excellent response, the oxide resistive thin film for a sensing material must have a high absolute value of a resistance temperature coefficient, that is, a resistance temperature coefficient.

In order to develop a highly sensitive infrared sensor at a high temperature, it is necessary for the oxide thin film for sensing material to have a high resistance temperature coefficient even at a high temperature. When an additive that maintains a valence state is added to the mother even when the temperature changes, The resistive thin film can have a high resistance temperature coefficient not only at room temperature but also at a high temperature of 80 to 120 占 폚.

Hereinafter, an oxide thin film for a bolometer according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG.

The oxide layer 120 can be made of a cubic spinel crystal structure in which an additive is added to the matrix of (Ni, Mn, Cu) ₃ O _4. The electrical characteristics of the cubic spinel crystal structure (AB ₂ O ₄ ) Electron hopping can be influenced by the difference in the valence of ions located in the octahedral octahedron. Electron hopping excites the electrons and moves electrons to nearby atoms while electrons move. In the spinel structure, the oxygen tetrahedron of A-site is largely empty, whereas the oxygen octahedrons of B-site are connected to the edge, which is closest to the distance. Therefore, the electron hopping is located in the oxygen octahedron, Lt; / RTI >

And Mn located at the B-site in the present invention exists in two different cations of Mn ^{3 +} and Mn ^{4 +,} to the charge difference between the electrons generated between the tetravalent 3 Kawagoe ion Mn ^{3 +} is a Mn ^{4 +,} Mn ^{4 +} is changed to Mn ^{3 +} . That is, the electrical characteristics of the thin film can be changed by the change of the ion charge (electron hopping) occurring between the Mn ^{3 +} and Mn ^{4 +} ions located at the B-site, and the resistivity and TCR change depending on the occurrence probability of the electron hopping can do.

As the ions of Mn ^{3 +} and Mn ^{4 +} are present in similar numbers in the B-site, the probability of electron-hopping between Mn ^{3 +} and Mn ^{4 +} increases as well as the resistivity as well as the resistivity (Ni, Mn, Cu) ₃ O an element for holding the valence state even when the temperature changes in the composition of the _four boron (B ^3+), zinc (Zn ^2+), gallium (Ga ^{+ 3),} indium (in ^{+ 3),} magnesium (Mg ^{+ 2)} , scandium (Sc ^{3 +)} and beryllium (Be ^{2 +)} of the at least one is when added as an additive as substituted with electron Mn ^{3 +} of the oxygen octahedral sites which hopping occurs Mn ^{3 +} and electron hopping probability between Mn ^{4 +} So that the resistivity and the TCR at high temperature can be increased.

In more detail, the both boron, zinc, gallium, indium, magnesium, scandium and beryllium as an element having a valence, the temperature change (Ni, Mn, Cu) as an additive in the matrix of ₃ O ₄ take a number of valence of (2) or (3), when the element which can maintain the valence state of divalent or trivalent is added without changing the valence even in the external influences such as temperature or pressure like the additive of the present invention, The valence of the valence of electrons), so that the electron hopping rate between Mn ^{3 +} and Mn ^{4 +} can be reduced by replacing an element not involved in electric conduction with Mn ^{3 +} of the octahedral octahedral. Accordingly, although the resistivity is somewhat increased, the change in resistance to the movement of electrons (or ions) due to the change in thermal energy is increased, so that the absolute value of TCR can be increased at a high temperature of 80 to 120 DEG C, It is possible to manufacture a bolometer having a good performance such as a shape.

On the other hand, for example, Cr ^{2 +,} Cr ^{3 +,} Cr ^{4 +,} Cr ^{5 +,} having a valence of Cr the (Ni, Mn, Cu) that varies in response to temperature changes brought the number of atoms of like Cr ^{6 +} as an additive ₃ O ₄ When added to the matrix, may be by Cr ^{3 +} and electron hopping of Cr ^{4 +} generated is of the A-site Cr and B-site of Mn substitution As done conductivity occurs, and the specific resistance and TCR decrease it. That ^{is, Cr, Bi (Bi 3+,} Bi 5 +), W (W 4+, W 5+, W 6+) is a valence of easily changing the additive element in response to temperature changes brought the number of atoms of elements such as , The electrons are hopped between the same cations having different valencies while being substituted with the element of B-site, and thus the electrical conductivity is increased. As a result, the electrical conductivity increases and the resistivity of the thin film can be decreased. So that the temperature resolution of the bolometer is poor.

The addition of the additive according to the embodiment of the present invention increases the TCR to improve the electrical characteristics at high temperature but also increases the resistivity. The specific resistance is 40? 占 내지 m to 60? 占 cm m, which is a resistivity applicable to microbolometer applications. The oxide resistive thin film for a bolometer according to the present invention can have a high TCR not only at room temperature but also at high temperature (80 DEG C to 120 DEG C), and at the same time, have an appropriate specific resistance.

Table 1 is a table showing binding valences of additives according to the embodiments of the present invention.

Cation The cationic bonding valence in the octahedron of oxygen Mn ^{3 +} 2.63 B ³⁺ 2.53 Zn ^{2 +} 1.73 Ga ^{3 +} 2.60 In ^{3 +} 2.54 Mg ^{2 +} 2.33 Sc ^{3 +} 2.55 Be ^{2 +} 1.60

Referring to Table 1, the additive is substituted with manganese located at the octahedral site of the cubic spinel crystal structure, and the bonding valence of the additive may be smaller than that of the manganese.

Another reason for the increase in TCR at room temperature and high temperature due to the addition of additives is the bond valence of B-sites in the cubic spinel crystal structure, The bond strength in a crystal can be analyzed and predicted because it is a function of distance between ions.

Referring to FIG. 2 and Table 1, it can be seen that the addition of the additive has a sheet resistance of less than 10 M? / Sq applicable to microbolometer applications, and a high TCR at room temperature and high temperature because the additive substituted with manganese The reduction of bond valence can be attributed to the bond strength between the ion and the oxygen ion of the additive located at the octahedral site, as well as the maintenance of one valence state, Of the total population.

As can be seen from Table 1, the bonding valence of at least one of boron, zinc, gallium, indium, magnesium, scandium and beryllium substituted with manganese in the octahedral site of AB ₂ O ₄ is 2.60 Or less. That is, when the additive of the present invention is added to the matrix of (Ni, Mn, Cu) ₃ O ₄ rather than the manganese in the octahedral site, the valence of the manganese is reduced when the manganese and the additive are substituted, Since the bonding force between the additive and the oxygen ion is weaker than the bonding force between the oxygen ions, the ions of the additive can easily move. Therefore, the rattling probability of the ion positioned at the octahedral site becomes higher as the temperature becomes higher, Lt; / RTI >

Therefore, the TCR can be attributed to the change of the valence bond of the octahedral site, so that not only the additive maintains a single valence state but also the bonding force with the oxygen ion decreases when the valence of the binding site of the octahedral octahedral is decreased, The rattling phenomenon that causes lattice scattering may occur more easily, so that the high temperature TCR may be higher.

Particularly, among the above elements, boron and zinc are used as additives for low-temperature sintering in bulk ceramics. When boron and zinc are added to the matrix according to the embodiment of the present invention as an additive, The heat treatment temperature can be lowered to 400 캜 or less, which can be more effective for the low temperature heat treatment.

More specifically, since boron has a low melting point in the form of oxides such as boric acid (H ₃ BO ₃ ) and boron trioxide (B ₂ O ₃ ), boron can be effective for low temperature heat treatment when added as an additive. ) Can act to promote densification at low temperatures and therefore may be effective for low temperature heat treatment when added as an additive. That is, when boron or zinc is added to the matrix, the heat treatment temperature for crystallization of the thin film may decrease, so that the oxide thin film having the cubic spinel crystal structure can be formed at a low heat treatment temperature range of 300 ° C to 400 ° C.

On the other hand, since the infrared sensor has noise due to heat, the specific resistance should be low in order to lower the noise characteristic of the infrared sensor. That is, since the oxide resistive thin film whose resistance value changes according to the temperature change due to the infrared absorption increases the noise of the bolometer due to the higher specific resistance, a low resistivity of 60 Ω · cm or less is required. In addition, System, there is a need for an oxide thin film for a bolometer having a high resistance temperature coefficient not only at a room temperature but also at a high temperature, in order to manufacture a bolometer with high sensitivity in various temperature ranges of room temperature and high temperature.

Table 2 shows electrical characteristics according to the content of additive (Zn).

Additive content 0wt% 4wt% 6wt% 8wt% 10wt% 12wt% 14wt% 17wt% Resistivity 17.6 26 34.4 42.8 51.1 58.5 82.3 108.4 Room temperature TCR -3.3 -3.22 -3.14 -3.05 -2.97 -2.92 -2.7 -2.5 High temperature TCR -1.93 -1.93 -1.94 -1.97 -1.98 -1.99 -2.02 -2.06

Referring to Table 2, the additive may be added in an amount of 8 wt% to 12 wt% with respect to the total weight of the matrix, and the absolute values of the room temperature resistance temperature coefficient and the high temperature resistance temperature coefficient of the oxide resistance thin film are 1.95% / K or more.

Additives include (Ni, Mn, Cu) ₃ O ₄ If the additive is added in an amount larger than 12 wt%, not only the spinel single phase but also the secondary phase is generated and the resistivity is increased, Can significantly increase the resistivity of the additive with a significant decrease in the electron-hopping probability between Mn ^{3 +} and Mn ^{4 +} . That is, when the content is larger than 12 wt%, the noise of the bolometer is increased due to high resistivity due to heat, which makes it difficult to realize the characteristics of the bolometer. On the other hand, when the additive is added in an amount of less than 8 wt%, the specific resistance is low and the TCR of the room temperature is high, but since the TCR at the high temperature is decreased, the high temperature environment There is a problem that it is difficult to use a high-sensitivity infrared sensor.

As described above, since the infrared sensor has noise due to heat, a specific resistance of less than 60? Cm is required for reducing the noise of the infrared sensor and outputting the optimum signal. However, it is better to have a lower resistivity value in the noise elimination and signal output, but when the specific resistance is smaller, the absolute value of the resistance temperature coefficient tends to decrease, so that the resistivity decreases and the TCR decreases. That is, when the resistivity is lower than 40 Ω · cm, the TCR at a high temperature may be reduced due to the influence on the TCR. Therefore, the oxide resistive thin film may have a high TCR while lowering the noise characteristic of the infrared sensor, cm. < / RTI >

Also, the absolute values of the room temperature resistance temperature coefficient and the high temperature resistance temperature coefficient of the oxide thin film according to the embodiment of the present invention may be 1.95% / K or more, respectively. The temperature resolution value of the infrared sensor is inversely proportional to the absolute value of the resistance temperature coefficient The absolute value of the resistance temperature coefficient should be large in order to improve the respon- sivity and the temperature resolution characteristic (NETD), which are important evaluation factors of the bolometer. However, when the absolute value of the resistance temperature coefficient, which is a measure of the sensing ability, is less than 1.95% / K, the response of the device and the temperature resolution characteristic are poor due to the absolute value of the low resistance temperature coefficient, , It is difficult to manufacture a device having a high sensitivity. Therefore, the absolute value of the room temperature resistance temperature coefficient and the high temperature resistance temperature coefficient of the oxide resistive thin film may be 1.95% / K or more, respectively.

On the other hand, although the absolute value of the resistance thermometer can be better in the road and temperature resolution side larger the response, as a (Ni, Mn, Cu) ₃ O _4-based additive of the present invention to the matrix is added to the oxide resistant thin film described above formed (1) an absolute value of a room temperature resistance temperature coefficient of 1.95% / K or more and (2) an absolute value of a high temperature resistance temperature coefficient of 1.95% / K or more, In order to satisfy all three conditions, the absolute value of the normal temperature and high temperature resistance temperature coefficient may be 3.1% / K or less. Therefore, the oxide-resistive thin film can have an absolute value of a high resistance temperature coefficient of 1.95% / K to 3.1% / K both at room temperature and at high temperature.

As described above, when the temperature is changed, not only the valence state is maintained but also the additive having the bonding valence of manganese having a smaller bonding valence is added to the (Ni, Mn, Cu) ₃ O ₄ system matrix in an amount of 8 wt% to 12 wt% The oxide resistive thin film of the present invention has an absolute value of a high resistance temperature coefficient of 1.95% / K or more at a high temperature as well as a room temperature, and at the same time, it can have a specific resistance of 60 Ω · cm or less applicable to microbolometer applications, A high sensitivity bolometer (or an infrared sensor) having both excellent precision and improved temperature stability can be manufactured at high temperature and high temperature.

 1B, an oxide seed layer 130 made of an oxide of at least one of nickel, manganese, and copper may be further disposed between the substrate 110 and the oxide layer 120 .

The oxide seed layer 130 provided on the substrate 110 may induce crystal growth of the oxide layer 120 formed on the oxide seed layer 130. The oxide seed layer 130 may be formed of nickel, Manganese, and copper may be provided as crystal nuclei in an oxidized state, the crystal growth of the oxide layer 120 may be facilitated. That is, the oxide seed layer 130 provides a crystal nucleus or a site to which the metal atoms necessary for forming the crystal structure of the resistive thin film 100 having the (Ni, Mn, Cu) ₃ O ₄ composition can adhere thereto So that the resistance thin film 100 can easily grow.

Therefore, the oxide seed layer 130 can provide the crystal nuclei necessary for forming the resistive thin film 100 of the spinel crystal structure, and can provide a position where crystals of the resistive thin film 100 can grow Therefore, the resistive thin film 100 having a composition of (Ni, Mn, Cu) ₃ O ₄ can be easily grown, and the resistance thin film 100 (100) can be easily grown at a low heat treatment temperature required for crystal growth, ) Can be formed.

FIG. 3 is a flowchart illustrating a method of manufacturing an oxide-resistive thin film according to another embodiment of the present invention, and FIG. 4 is a cross-sectional view illustrating a structure of a spin coater according to another embodiment of the present invention.

Referring to FIGS. 3 to 4, the method for producing an oxide-resistant thin film for a bolometer according to another embodiment of the present invention includes the steps of: preparing a plurality of metal oxide organic compounds and an additive for maintaining the valence state, Preparing a plurality of precursor precursor solutions and an additive solution; Preparing a mixed solution by mixing the plurality of pre-precursor solutions and the additive solution; Diluting the mixed solution with a second organic solvent different from the first organic solvent to prepare a precursor solution; Forming a precursor layer on the substrate by a liquid phase process using the precursor solution; And a step of converting the precursor layer into an oxide layer by performing a subsequent heat treatment in an oxidizing atmosphere.

First, a plurality of pre-precursor solutions and additive solutions can be prepared by dissolving each of the plurality of metal oxide organic compounds and the additive that maintains a valence state in the first organic solvent even when the temperature is changed (S100). At this time, the first organic solvent may be an aromatic hydrocarbon-based organic solvent.

A plurality of preliminary precursor solutions and additive solutions can be prepared by dissolving a plurality of metal oxide organic compounds and an additive solution in a first organic solvent before preparing the mixed solution, respectively, and a plurality of metal oxide organic compounds and additives are dissolved the first organic solvent is benzene (C ₆ H _6), toluene _{(C 6 H 5 CH 3)} , xylene _{(C 6 H 4 (CH 3} ) 2), naphthalene (C ₁₀ H _8), anthracene (C ₁₄ H ₁₀ ) And aromatic hydrocarbon-based organic solvents.

In general, metal oxide organic compounds having carboxylate groups and additives are nonpolar materials which are not soluble in polar solvents such as water and may have a long chain length. Materials with long chain or complex hydrocarbon (CH) chains, such as carbon compounds, have non-polar and hydrophobic properties that are insoluble in polar solvents. As the chain length increases, hydrophobic properties increase. Since the solubility is reduced, it is soluble in a polar solvent when it has a short chain, whereas it is not well soluble in a polar solvent when it has a long chain.

Thus, metal oxide organic compounds and additives having low polarity due to their long chain lengths, which are hydrophobic, can be more soluble in non-polar solvents such as benzene, toluene, xylene and the like than polar solvents due to their hydrophobic properties, so that a plurality of pre- And the additive solution can be prepared by respectively dissolving in a first organic solvent which is an aromatic hydrocarbon organic solvent and the metal oxide organic compound can be more effectively dissolved in the first organic solvent as described above, It is possible to easily control the molarity, that is, the molar concentration of each composition, so that a precursor solution having a desired composition can be easily obtained.

A plurality of preliminary precursor solutions and additive solutions may be prepared, and a mixed solution may be prepared by mixing solutions of the respective precursor precursors at predetermined ratios with an additive solution (S200). Before mixing with the additive solution In the present invention, in one embodiment, the oxide layer 120 is formed of [(Ni, Mn) _1-x Cu _x ] ₃ O ₄ (x = 0.3).

Wherein the oxide layer comprises a (Ni, Mn, Cu) ₃ O ₄ based matrix and an additive added to the matrix, the additive being an element that maintains a valence state even when the temperature changes, To 8 wt% to 12 wt%.

Referring again to Table 2, when the additive is added in an amount larger than 12 wt%, not only the spinel single phase but also the secondary phase is generated and the resistivity is increased. In addition, the additive having one atomic valence increases electrons between Mn ³⁺ and Mn ⁴⁺ The resistivity may increase sharply while greatly reducing the hopping probability. That is, when the content is larger than 12 wt%, the noise of the bolometer generating noise due to heat due to the high resistivity may be increased, which makes it difficult to realize the characteristics of the bolometer. On the other hand, when the additive is added at a content of less than 8 wt%, the TCR at high temperature is decreased, so that there is a problem in that the use of the high-sensitivity infrared sensor is restricted in a high temperature environment such as a vehicle having a high temperature by environmental or device heating .

In the plurality of metal oxide organic compounds such that the oxide layer 120 has the above composition, the plurality of metal oxides may be nickel oxide, manganese oxide, and copper oxide, and a plurality of metal oxide organic compounds are respectively dissolved in the first organic solvent pre-precursor solutions of the prepared plurality may be in one embodiment _{NiO, Mn 2 O 3, CuO} .

The additive may include at least one element selected from the group consisting of boron, zinc, gallium, indium, magnesium, cesium and beryllium, and the bonding valence of the additive may be smaller than the bonding valence of the manganese.

Boron (B ^3+), zinc (Zn ^{+ 2),} gallium (Ga ^{+ 3),} indium (In ^{+ 3),} magnesium (Mg ^{+ 2),} scandium (Sc ^{3 +)} and beryllium (Be ^{+ 2),} all As an element having one valence, an additive solution can be prepared by dissolving an additive which maintains a predetermined valence state such as boron, zinc, gallium, indium, magnesium, scandium and beryllium in the above-mentioned first organic solvent, The additive that can maintain only one atomic state without changing the valence is dissolved in the first organic solvent and mixed with the plurality of precursor precursors, a single valence stable in the cubic spinel crystal structure crystallized by the subsequent heat treatment or a trivalent atom) to as get the element that does not engage the additive in the electrically conductive substituted and Mn ^{3 +} of the oxygen octahedral sites by reducing the Mn ^{3 +} and electron hopping between Mn ^{4 +} ratio, but the specific resistance is increased, the thermal energy changes Another electron (or ion) is increased the resistance change of the movement of the TCR can be increased at high temperature.

The bonding valence of at least one of boron, zinc, gallium, indium, magnesium, scandium, and beryllium substituted with manganese in the octahedral octahedral site of the cubic spinel crystal structure crystallized by the subsequent heat treatment is 2.63 (Ni, Mn, Cu) ₃ O ₄ , the additive according to the embodiment of the present invention is added to the octahedral site of the oxyalkylene compound to lower the bonding force between the manganese and the oxygen ion The bonding force with oxygen ions is weakened and the additive ions can move easily, so that the rattling probability of the metal ion at high temperature is increased and the high temperature TCR can be improved.

Particularly, boron and zinc among the elements satisfying the above two conditions are used as additives for low-temperature sintering in bulk ceramics unlike gallium, indium, magnesium, scandium and beryllium. As a result, In the present invention, when at least one of boron and zinc is added as an additive to the matrix in the present invention, the heat treatment temperature required for crystal growth can be reduced, which is more effective for low temperature heat treatment.

After the mixed solution is prepared, the precursor solution 100 may be prepared by diluting the mixed solution with a second organic solvent different from the first organic solvent (S300). At this time, the second organic solvent may be acetic acid ester-based organic solvent.

The precursor solution 100 coated on the substrate 110 may be prepared by diluting the mixed solution with a second organic solvent different from the first organic solvent. The second organic solvent may be ethyl acetate (C ₄ H ₈ O ₂ ) , Acetic acid esters such as butyl acetate (C ₆ H ₁₂ O ₂ ), methyl acetate (C ₃ H ₆ O ₂ ), cellosolve acetate (C ₆ H ₁₂ O ₃ ), and carbitol acetate (C ₁₀ H ₂₀ O ₄ ) It can be used daily for organic.

The second organic solvent may be prepared by dissolving an organic solvent such as an acetate ester organic solvent containing oxygen atoms in an organic solvent different from the first organic solvent in consideration of the contact angle or wettability with the substrate 110 when the prepared precursor solution 100 is coated on the substrate 110. [ Such second organic solvent may increase the wettability of the substrate 110 and increase the surface energy so that effective adhesion with the substrate 110 may occur. In other words, when the precursor solution 100 using the second organic solvent containing oxygen atoms is applied on the substrate 110, the contact angle with the substrate 110 is minimized to improve the wettability of the precursor solution 100, It is possible to effectively improve the adhesion with the adhesive layer 110.

Accordingly, by using the second organic solvent having an oxygen atom different from the first organic solvent in the preparation of the precursor solution, the substrate 110 can be formed without oxygen plasma treatment in order to impart adhesiveness and hydrophilicity to the surface of the substrate 110. [ And the oxide-resistance thin film 340 can be improved.

In the present invention, precursor solution (100) is not prepared using one organic solvent, and the precursor solution (100) is prepared in two stages using different first organic solvent and second organic solvent, And the additive can be more effectively dissolved and the adhesion with the substrate 110 can be improved. When the precursor solution 100 is prepared by dissolving the metal oxide organic compound and the additive in the second organic solvent without dissolving the first organic solvent in the first organic solvent, the adhesion to the substrate 110 can be improved, Since the second organic solvent of the second organic solvent is a polar solvent, the metal oxide organic compound having a long chain length and the additive are not dissolved sufficiently, so that the oxide-resistant thin film 340 may not be produced.

Therefore, by dissolving the metal oxide organic compound having a long chain length and the additive in the first organic solvent which is a non-polar solvent, it is possible to dissolve the organic metal compound and the additive more effectively than the second organic solvent which is a polar solvent, 2 organic solvent, the bonding property between the substrate 110 and the oxide-resistant thin film 340 can be improved.

The precursor solution 100 may be formed on the substrate 110 prior to forming the precursor layer 125 with the precursor solution 100. The precursor solution 100 may include at least one of the plurality of metal oxides, The metal layer may further include a metal layer, and the metal layer may be formed by physical vapor deposition.

Since the precursor layer 125 formed by coating the precursor solution on the metal layer (or the pre-oxide seed layer) is oxidized by the subsequent heat treatment to be changed into the oxide layer 120, the metal layer according to the present invention is a metal oxide If at least one of the metals of the organic compound is oxidized and provided as crystal nuclei, the crystal growth of the oxide layer 120 may be easier. That is, the metal layer may include at least any one metal among the plurality of metal oxides described above, more specifically, at least one of nickel, manganese, and copper to serve as a nucleus at the bottom of the oxide layer 120 , The metal atoms of the metal layer can provide a position where the crystal nuclei to which the metal atoms necessary for forming the resistive thin film 340 of the spinel crystal structure can adhere and the crystal of the resistive thin film 340 can grow, (340) can easily grow.

The metal layer formed on the substrate 110 can be deposited by a physical vapor deposition method, that is, a sputtering deposition method. Since the sputtering deposition method is a conventional method, a detailed description will be omitted.

The method may further include a step of preheating the metal layer at a temperature lower than the temperature of the next heat treatment to form the oxide seed layer 130 before forming the precursor layer 125 after forming the metal layer.

At least any one metal of nickel, manganese, and copper in the metal layer may be changed to an oxide seed layer 130 to serve as a crystal nucleus. The preliminary heat treatment can be performed at a lower temperature than the subsequent heat treatment. That is, to facilitate crystal growth of the oxide layer 120, a preliminary heat treatment for oxidation of the metal layer in an oxygen atmosphere or atmosphere at a lower temperature than the subsequent heat treatment is performed to change the metal layer to a preliminary oxide seed layer serving as a seed layer .

In this case, since the pre-oxide seed layer changed by the preliminary heat treatment of the metal layer is not in a state of being coupled with the oxide layer 120 before the precursor layer 125 is changed to the oxide layer 120 through the subsequent heat treatment, But may be a pre-oxide seed layer for serving as a seed layer.

Since the precursor layer 125 formed on the oxide seed layer 130 is changed to the oxide layer 120 through the subsequent heat treatment, the metal layer (for example, the copper metal layer) subjected to the preliminary heat treatment is changed from Cu to CuO x, And may be a pre-oxide seed layer that facilitates crystal growth of the oxide layer 120 that is ultimately formed on the pre-oxidized seed layer, which is an oxidized metal layer.

The precursor layer 125 is not subjected to a preliminary heat treatment for oxidizing the metal layer to change it to the preliminary oxide seed layer. Even if the preliminary heat treatment is not performed before the precursor layer 125 is formed, The oxide seed layer 130 may be a metal layer oxidized by oxidizing not only the precursor layer 125 but also the metal layer.

Therefore, the pre-oxide seed layer for serving as the seed layer can provide the crystal nuclei necessary for forming the resistive thin film 340 of the spinel crystal structure, and the position where the crystal of the resistive thin film 340 can grow The resistive thin film 340 having a composition of (Ni, Mn, Cu) ₃ O ₄ can be easily grown.

The precursor layer 125 may be formed by a liquid phase process using the spin coater and precursor solution 100 as shown in FIG. 4 on the substrate 110 (S400) after changing the metal layer to a pre-oxide seed layer.

The substrate 110 on which the preliminary oxide seed layer (not shown) is formed is placed on the support unit 210 and the precursor solution 100 is injected onto the preliminary oxide seed layer using the nozzle 220. The substrate 110 can be rotated by rotating the support unit 210 while applying the precursor solution 100 onto the pre-oxide seed layer. Thus, the precursor solution 100 can be coated so as to have a stable thickness on the pre-oxide seed layer while being evenly spread.

Since the solvent or organic residues contained in the precursor layer 125 formed by coating the precursor solution 100 may degrade the quality of the resistive thin film 340, the organic solvent or organic residues in the precursor layer 125 may be removed A preliminary subsequent heat treatment may be performed at a lower temperature and a faster holding time than the subsequent heat treatment before performing the subsequent heat treatment.

The metal organic decomposition method can maintain the desired stoichiometric ratio by the wet chemical thin film production method using the precursor solution 100. The metal organic decomposition method can quickly manufacture the resistive thin film 340 on the substrate 110 without a vacuum device and a simple process There is an advantage to be able to do. Although the precursor layer 125 according to the present invention is formed by the metal organic decomposition method, the present invention is not limited thereto and various liquid phase processes can be selected.

The precursor layer 125 may be subjected to a subsequent heat treatment in an oxidizing atmosphere to convert the precursor layer 125 into the oxide layer 120. In operation S500, the precursor layer 125 may be annealed in an oxidizing atmosphere to remove the organic solvent or organic residues. At this time, the subsequent heat treatment may be performed at a temperature ranging from 300 ° C to 400 ° C.

The precursor layer 125 formed on the pre-oxide seed layer can be changed to oxide layer 120 and improved to be as close to densification and crystallization or high resistance temperature coefficient, low resistivity, low 1 / f noise, good environmental stability The precursor layer 125 may be subjected to a subsequent heat treatment.

As the subsequent heat treatment of the precursor layer 125 formed on the pre-oxide seed layer proceeds, the precursor layer 125 turns into the oxide layer 120, where the precursor layer 125 changes into the oxide layer 120 through a subsequent heat treatment The metal oxide crystal grains of the oxide layer 120 and the metal oxide crystal grains of the preliminary oxide seed layer formed below the oxide layer 120 are coupled to each other so that the preliminary oxide seed layer provides crystal nuclei to the oxide layer 120 To the oxide seed layer 130 of the spinel crystal structure. That is, the nickel, manganese, and copper crystal grains of the oxide layer 120 can be diffused and penetrated into the pre-oxide seed layer formed under the oxide layer 120, so that the pre-oxide seed layer becomes the same as the oxide layer 120 And an oxide seed layer 130 having a spinel crystal structure having a composition of (Ni, Mn, Cu) ₃ O ₄ .

In order to minimize the thermal conduction from the surrounding environment to the resistive film 340 when forming the bolometer, the resistive film 340 is separated from the substrate 110 by the spacing space 360 without being in contact with the substrate 110, An organic material sacrificial layer 330 such as polyimide (PI) may be formed on the resistive thin film 340. Generally, in the case of the resistive thin film 340 deposited only by the metal organic decomposition method, a subsequent heat treatment temperature for crystallizing the resistive thin film 340 is A bubbling problem in which the organic material of the organic material sacrifice layer 330 boils up may occur because the temperature of the resistive thin film 340 is higher than 450 DEG C, and the damage of the readout integrated circuit and the thermal expansion coefficient Deformation due to mismatch may occur. Therefore, a lower heat treatment temperature of 400 占 폚 or less may be required to completely prevent the damage and bubbling problem of the readout integrated circuit caused by the high heat treatment temperature.

The subsequent heat treatment according to an embodiment of the present invention can be performed at a temperature ranging from 300 ° C to 400 ° C. In the present invention, the additive added to the matrix of the present invention not only improves the TCR at room temperature and high temperature of the thin film, Since the sintering temperature can be reduced by the additive for sintering, the subsequent heat treatment temperature necessary for crystallization can be reduced to 400 캜 or lower, and the oxide thin film 340 can be stably manufactured without heat treatment at a high temperature.

If the subsequent heat treatment necessary for the crystallization is performed at a temperature of less than 300 ° C., the temperature may not be sufficiently high and the precursor layer 125 may not be changed to the oxide layer 120, so that the resistive thin film 340 has a spinel crystal structure Can not be formed. In addition, if the subsequent heat treatment is performed at a temperature exceeding 400 캜, the heat treatment temperature may be too high as described above, and the burying problem of the organic sacrificing layer 330 may occur.

Therefore, the subsequent heat treatment at 300 ° C to 400 ° C is a temperature lower than the temperature at which the subsequent heat treatment is performed at a temperature higher than 450 ° C. Therefore, when the resistive thin film 340 according to the present invention is applied to the resistive thin film 340 for actual bolometer, The problem of damaging the read integrated circuit formed in the lower substrate 110 caused by the process of forming the organic thin film 330 can be fundamentally prevented and the polyimide bubbling problem of the organic sacrificial layer 330 can be completely solved, Can be used easily.

5 is a sectional view showing a manufacturing process of a bolometer according to still another embodiment of the present invention.

Referring to FIG. 5, a method of manufacturing a bolometer according to another embodiment of the present invention includes: providing a substrate 310 on which a signal processing circuit is formed; Forming a plurality of metal pads (320) spaced apart from the upper surface of the substrate (310) to transmit an electric signal of the signal processing circuit; Forming an organic sacrificial layer (330) on the substrate (310); Forming an oxide resistive thin film (340) on the organic sacrificial layer (330) by the method of any one of the preceding claims; And patterning the organic sacrificial layer 330 and the oxide-resistive thin film 340.

First, a substrate 310 on which a signal processing circuit (not shown) is formed can be provided (FIG. 5A). The substrate 310 may include a signal processing circuit for detecting infrared rays, and may be a SiNx wafer or a semiconductor material such as silicon, but the material and structure thereof are not particularly limited.

A metal pad 320 electrically connected to the signal processing circuit may be deposited on the substrate 310 on which the signal processing circuit is formed by a physical vapor deposition method such as a sputtering deposition method. The metal pads 320 may be deposited by physical vapor deposition, but not limited thereto, by various deposition methods.

After the metal pads 320 are deposited, a photosensitive liquid is coated on the metal pads 320, exposed, developed, and etched so as to leave the metal pads 320 only at desired portions by a photolithography process, And a metal pad 320 pattern that is electrically connected to the signal processing circuit can be formed. The metal pad 320 may be connected to the resistance thin film 340 in contact with the conductive material of the support member 350, which will be described later.

The organic sacrificial layer 330 may then be applied to the substrate 310 having the metal pad 320 formed thereon by spin coating or the like to form a spacing space 360 to be described later ). The organic sacrificial layer 330 may utilize a polyimide that is generally stable at high temperatures.

After forming the organic sacrificial layer 330, the oxide resistive thin film 340 may be formed on the organic sacrificial layer 330 by any one of the methods described above.

The method for preparing the oxide-resistant thin film (340) comprises: preparing a plurality of pre-precursor solutions and additive solutions by dissolving a plurality of metal oxide organic compounds and an additive that maintains a valence state even when the temperature changes; Preparing a mixed solution by mixing the plurality of pre-precursor solutions and the additive solution; Diluting the mixed solution with a second organic solvent different from the first organic solvent to prepare a precursor solution; Forming a precursor layer on the substrate by a liquid phase process using the precursor solution; And a step of converting the precursor layer into an oxide layer by performing a subsequent heat treatment in an oxidizing atmosphere.

The first organic solvent in which the plurality of metal oxide organic compounds and the additives are dissolved is toluene (C ₆ H ₅ CH ₃ ), xylene (C ₆ H ₄ (CH ₃ ) ₂ ), naphthalene (C ₁₀ H ₈ ) C ₁₄ H ₁₀ ), and the second organic solvent for diluting the mixed solution is an organic solvent such as ethyl acetate (C ₄ H ₈ O ₂ ), butyl acetate (C ₆ H ₁₂ O ₂ ), methyl acetate (C ₃ H ₆ O ₂ ), cellosolve acetate (C ₆ H ₁₂ O ₃ ), and carbitol acetate (C ₁₀ H ₂₀ O ₄ ).

More specifically, metal oxide organic compounds and additives having a small polarity and having a small polarity can not be dissolved in a polar solvent because they have a long chain length and can be more easily dissolved in non-polar solvents such as benzene, toluene, xylene and the like due to their hydrophobic properties A plurality of preliminary precursor solutions and additive solutions can be prepared by first dissolving a plurality of metal oxide organic compounds in a first organic solvent which is a non-polar solvent, respectively.

(2) an additive (boron or zinc) capable of low-temperature sintering has a main bonding composition which has (1) a binding valence that is smaller than the bonding valence of ions located at the octahedral site, To 60%? 占 cm m, which can be applied to microbolometer applications at the same time while having a high TCR of from -1.95% / K to -3.1% / K at high temperature as well as at room temperature when added in an amount of 8 wt% to 12 wt% And the heat treatment temperature for crystallization of the thin film can be lowered to 400 DEG C or less.

A precursor solution 100 may be prepared by diluting a mixed solution obtained by mixing a plurality of preliminary precursor solutions and an additive solution with a second organic solvent different from the first organic solvent, Since the organic solvent of the organic solvent includes oxygen atoms, the bondability between the substrate 110, 310 and the resistance thin film 340 can be improved.

The oxide-resistive thin film 340 manufactured in this manner can have a high TCR of -1.95% / K to -3.1% / K at room temperature and high temperature, and at the same time, have an appropriate specific resistance.

The method of manufacturing the oxide-resistive thin film 340 formed on the organic sacrificial layer 330 is the same as the embodiment described with reference to FIGS. 3 to 4, and therefore, a detailed description will be made with reference to FIG. 3 to FIG.

When the organic sacrificial layer 330 and the oxide resistive thin film 340 are formed on the substrate 310, a photosensitive liquid is applied on the resistive thin film 340 and the organic sacrificial layer 330 and the resistive layer 340 are formed only by a photolithography process, The organic sacrificial layer 330 and the resistive thin film 340 may be patterned by exposing, developing and etching the remaining thin film 340 to expose a part of the metal pad 320 (FIG. 5C).

Next, the method may further include forming a support member 350 having one side connected to the metal pad 320 and the other side connected to the resistance thin film 340 (FIG. 5D).

The support member 350 supports the resistance thin film 340 by connecting the metal pad 320 and the resistance thin film 340. The support member 350 may include at least a pair of May be formed in the shape of a support member 350.

The resistance thin film 340 can be brought into contact with the lower surface of the protruding portion of the support member 350 and can have sufficient mechanical strength to support the resistance thin film 340 while minimizing the thermal conductivity And may be made of a material having thermal conductivity and formed to have a small cross-sectional area. That is, a single or composite metal such as aluminum, titanium, or tungsten may be used for conductivity and mechanical stability.

The supporting member 350 may further include a conductive layer (not shown) electrically connecting the substrate 310 and the resistive thin film 340. The conductive layer of the supporting member 350 may include a resistance thin film 340, And a conductive material for electrically connecting the signal processing circuit with the signal processing circuit.

The support member 350 not only functions to support the resistance thin film 340 but also forms the resistance thin film 340 and the metal pad 320 through the conductive material So that the signal processing circuit can be electrically connected.

Then, the organic sacrificial layer 330 may be removed (FIG. 5E).

The organic sacrificial layer 330 may be plasma-ignited using a reactive gas containing oxygen to form a spacing space 360 as shown in FIG. 5E. The space between the substrate 310 on which the organic sacrificial layer 330 is formed and the resistive film 340 is left in the spacing space 360 and the optical resonance structure can be provided by the spacing interval of the spacing space 360 . Therefore, in order to minimize the thermal conduction from the surrounding environment to the resistive thin film 340 for the bolometer, the resistive thin film 340 may be spaced apart by the spacing space 360 without being in contact with the substrate 310.

Although the present invention has been described in detail with reference to the specific embodiments thereof, it will be apparent to those skilled in the art that various modifications and variations can be made without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited by the described embodiments, but should be defined by the appended claims, as well as the appended claims.

100: precursor solution 110, 310: substrate
120: oxide layer 125: precursor layer
130: oxide seed layer 210: support unit
220: nozzle 320: metal pad
330: organic sacrificial layer 340: oxide resistive thin film
350: support member 360: spacing space

Claims (16)

delete delete delete delete delete delete Preparing a plurality of pre-precursor solutions and additive solutions by dissolving a plurality of metal oxide organic compounds and an additive that maintains a valence state even when the temperature changes, in each of the first organic solvents;
Preparing a mixed solution by mixing the plurality of pre-precursor solutions and the additive solution;
Diluting the mixed solution with a second organic solvent different from the first organic solvent to prepare a precursor solution;
Forming a precursor layer on the substrate by a liquid phase process using the precursor solution; And
And a step of subjecting the precursor layer to a subsequent heat treatment in an oxidizing atmosphere to change into an oxide layer.
The method of claim 7,
Wherein the oxide layer comprises a (Ni, Mn, Cu) ₃ O ₄ based matrix and an additive which is added to the matrix and is an element that maintains a valence state even when the temperature changes,
Wherein the additive is added in an amount of 8 wt% to 12 wt% with respect to the total weight of the mother body.
The method of claim 7,
Wherein the plurality of metal oxides include nickel oxide, manganese oxide, and copper oxide,
Wherein the bonding valence of the additive is smaller than that of the manganese.
The method of claim 7,
Wherein the additive comprises at least one element selected from the group consisting of boron, zinc, gallium, indium, magnesium, cesium and beryllium.
The method of claim 7,
Wherein the first organic solvent is an aromatic hydrocarbon organic solvent.
The method of claim 7,
Wherein the second organic solvent is an acetate-based organic solvent.
The method of claim 7,
Wherein the subsequent heat treatment is performed in a temperature range of 300 ° C to 400 ° C.
The method of claim 9,
Before the process of forming the precursor layer,
And forming a metal layer including at least one of the plurality of metal oxides on the substrate.
15. The method of claim 14,
Wherein the metal layer is formed by physical vapor deposition.
15. The method of claim 14,
Before forming the metal layer and forming the precursor layer,
Further comprising the step of subjecting the metal layer to a preliminary heat treatment at a temperature lower than that of the subsequent heat treatment to change into an oxide seed layer.

Images