KR102620734B1 - Bolometer Infrared Sensors to Minimize Output Change Due to High Temperature of Targets - Google Patents

Abstract

Disclosed is a bolometer infrared sensor for minimizing output changes caused by high temperature targets.
A bolometer infrared sensor according to an embodiment of the present invention includes a sensor substrate including a signal layer for transmitting electrical signals of a signal acquisition circuit; a contact pad connected to the signal layer of the sensor substrate and for electrical connection; a support pillar connected to the contact pad on one side and connected to the connection bridge layer on the other side; a connection bridge layer connected on one side to the support pillar and on the other side connected to a resistor layer; a resistive layer connected to the connecting bridge layer and having variable resistance depending on temperature; a blocking film layer formed in contact with the resistive layer to block infrared rays; and a heat conduction layer located between the resistor layer and the sensor substrate, and a portion of the heat conduction layer connected to the sensor substrate.

Description

Bolometer Infrared Sensors to Minimize Output Change Due to High Temperature of Targets}

The present invention relates to a bolometric infrared sensor for minimizing output changes caused by targets exposed to high temperatures.

The content described in this section simply provides background information on embodiments of the present invention and does not constitute prior art.

The core of the bolometer infrared sensor is to convert the change in temperature caused by absorbing infrared energy incident from the target object into a change in electrical resistance, and to read the change in current due to this change in electrical resistance through a signal acquisition circuit. .

The reference cell must generate a constant offset current without reacting to infrared energy, so that the base current flowing in the reactor cell can be removed so that only the current component modulated by infrared energy can be detected. For this reason, the thermal conductivity must be designed to be large so that heat can escape easily, so it is mainly constructed in a form where there is no connecting leg and the resistor is directly connected to the support pillar, or an additional thermal conductive portion with high thermal conductivity is constructed, or it is constructed on the sensor board. It is composed immediately without any separation.

In the case of a structure with high thermal conductivity, there is no problem in general use, but when infrared rays are incident from a high temperature target, image unevenness occurs. In other words, when high infrared energy is incident from a high temperature target such as the sun, the absorbed infrared energy cannot be emitted and pattern noise in the image is generated. To solve this problem, a reflector is formed on the surface of the reference cell to minimize infrared absorption. Each company uses a structure with high thermal conductivity, forms a reflective layer directly on the blind cell, or forms a reflective structure spaced apart on top of the reflective layer. take a method A technology in which thermal stability at high temperatures is impaired by increasing the temperature of the reference cell without dissipating the residual heat of the operating current as the heat capacity increases when a blocking film is formed by contacting the upper part of the reference cell is described in Korean Patent No. 10-1442811. .

However, when forming an additional reflective layer (blocking film), the steps in the manufacturing process of the bolometer infrared sensor increase, and due to the characteristics of the semiconductor process, this becomes a factor in increasing unit costs and lowering yield.

The present invention relates to a bolometric infrared sensor that absorbs infrared rays and modulates them into electrical signals. The present invention relates to a bolometric infrared sensor that absorbs infrared rays and modulates them into electrical signals. The present invention relates to a bolometer-type infrared sensor that minimizes output changes caused by high-temperature targets to improve output signal uniformity degradation due to unwanted temperature changes in reference cells caused by high-temperature targets. The main purpose is to provide a bolometer infrared sensor to do this.

According to one aspect of the present invention, a bolometric infrared sensor for achieving the above object is a bolometric infrared sensor for minimizing output changes caused by a high temperature target, comprising: a sensor substrate including a signal layer for transmitting electrical signals of a signal acquisition circuit; a contact pad connected to the signal layer of the sensor substrate and for electrical connection; a support pillar connected to the contact pad on one side and connected to the connection bridge layer on the other side; a connection bridge layer connected on one side to the support pillar and on the other side connected to a resistor layer; a resistive layer connected to the connection bridge layer and having variable resistance depending on temperature; a blocking film layer formed in contact with the resistive layer to block infrared rays; and a heat conduction layer located between the resistor layer and the sensor substrate, and a portion of the heat conduction layer connected to the sensor substrate.

As described above, the present invention has the effect of providing a bolometric infrared sensor that can minimize output changes in a high temperature environment by adding a barrier layer to the reference cell.

In addition, the present invention has the effect of lowering the manufacturing cost and increasing yield by adding a barrier layer to the reference cell without adding a process step for manufacturing the bolometer infrared sensor.

1 is a diagram showing an infrared detector including a bolometric infrared sensor according to an embodiment of the present invention.
2A and 2B are diagrams showing a reference cell of a bolometric infrared sensor according to a first embodiment of the present invention.
Figure 3 is a diagram for explaining the manufacturing process of a reference cell according to the first embodiment of the present invention.
4A and 4B are diagrams showing a reference cell of a bolometer infrared sensor according to a second embodiment of the present invention.
Figure 5 is a diagram for explaining the manufacturing process of a reference cell according to a second embodiment of the present invention.
Figures 6a and 6b are diagrams showing a reactant cell of a bolometer infrared sensor according to an embodiment of the present invention.
Figure 7 is a diagram for explaining the manufacturing process of a reactant cell according to an embodiment of the present invention.
Figure 8 is a circuit diagram showing a detection circuit in which a reactant cell and a reference cell are connected to a signal acquisition circuit according to an embodiment of the present invention.
Figure 9 is an exemplary diagram showing the output of an infrared image using a bolometer infrared sensor according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. In describing the present invention, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present invention, the detailed description will be omitted. In addition, preferred embodiments of the present invention will be described below, but the technical idea of the present invention is not limited or restricted thereto, and of course, it can be modified and implemented in various ways by those skilled in the art. Hereinafter, with reference to the drawings, a detailed description will be given of the bolometer infrared sensor for minimizing output change caused by a high temperature target proposed in the present invention.

1 is a diagram showing an infrared detector including a bolometric infrared sensor according to an embodiment of the present invention.

Figure 1(a) shows the infrared detector 10, and Figure 1(b) shows the configuration of the infrared detector 10. The infrared detector 10 according to this embodiment includes an infrared window 100, an infrared sensor 200, and a feedthrough unit 300. The infrared detector 10 of FIG. 1 is according to one embodiment, and not all blocks shown in FIG. 1 are essential components. In other embodiments, some blocks included in the infrared detector 10 may be added, changed, or deleted. It can be.

The infrared detector 10 refers to a transducer that absorbs infrared rays and modulates them into electrical signals. The infrared detector 10 maintains its interior in a vacuum state to preserve the absorbed infrared energy.

The infrared window 100 selectively transmits only infrared wavelengths.

The infrared sensor 200 refers to a semiconductor sensor that absorbs infrared rays and modulates them into electrical signals.

The infrared sensor 200 refers to a bolometer-type infrared sensor that absorbs infrared rays and modulates them into electrical signals.

The infrared sensor 200 may be implemented in a form that includes at least one cell among a reactant cell 210 and a reference cell 220.

The reactant cell 210 absorbs infrared energy and generates an electric signal by changing resistance according to temperature change. The configuration of the reactant cell 210 will be described in detail in FIGS. 6 and 7.

The reference cell 220 performs an operation of not absorbing infrared rays in order to amplify only the magnitude of the modulated current by removing the reactant cell 210 and the unmodulated basic current of the reactant cell 210. The configuration of the reference cell 220 will be described in detail in FIGS. 2 to 5.

The feed through unit 300 transmits the input for operating the infrared sensor 200 and the electrical output generated by infrared rays to the outside.

2A and 2B are diagrams showing a reference cell of a bolometric infrared sensor according to a first embodiment of the present invention.

FIG. 2A shows a top view of the reference cell 220 of the bolometric infrared sensor according to the first embodiment, and FIG. 2B shows a cross-sectional view of the reference cell 220 of the bolometric infrared sensor according to the first embodiment.

In general, the reference cell does not react to infrared energy and generates a constant offset current by removing the base current flowing in the reactor cell so that only the current component modulated by infrared energy can be detected. For this reason, the reference cell must be designed to have high thermal conductivity so that heat can escape well, so it is mainly composed of a form without connecting legs and a resistor directly connected to the support pillar, or an additional heat conduction part with high thermal conductivity is formed, or It may be configured to contact the sensor substrate without separation.

However, when high infrared energy is incident, all of the infrared energy absorbed by the reference cell cannot be discharged, resulting in distortion of the image.

The reference cell 220 of the bolometer infrared sensor according to the first embodiment has a structure to improve output signal uniformity degradation due to unwanted temperature changes in the reference cell due to a high temperature target.

The reference cell 220 according to the first embodiment forms a blocking film that cannot absorb infrared rays in order to fundamentally block image distortion caused by not discharging all of the absorbed infrared energy.

The reference cell 220 according to the first embodiment generates a barrier layer 20 at the same time as creating a support pillar 224 formed to support the structure and transmit an electrical signal, thereby transmitting infrared energy without an additional manufacturing process. It is possible to prevent image distortion caused by not being able to discharge everything. The support pillar 224 and the barrier layer 20 according to the first embodiment may be formed of metal materials such as titanium (Ti), nickel (Ni), copper (Cu), and aluminum (Al). The thickness of the barrier layer 20 is preferably 100 nm or more, and is preferably thick enough to reflect infrared rays in the 8 to 14 μm far infrared (LWIR: Long Wavelength InfraRed) wavelength band.

Meanwhile, in the first embodiment, it is assumed that the reference cell is designed so that the heat conduction layer 228 remains so that the absorbed infrared energy escapes to the signal acquisition circuit board 227.

Hereinafter, the configuration of the reference cell 220 of the bolometer infrared sensor according to the first embodiment will be described.

The reference cell 220 according to the first embodiment includes a sensor substrate 227, a contact pad 225, a support pillar 224, a connection bridge layer 22, a resistor layer 21, a barrier layer 20, and a heat shield layer 220. It includes a conductive layer (228).

The sensor substrate 227 includes a signal layer 226 for transmitting electrical signals of the signal acquisition circuit.

The contact pad 225 is formed between the signal layer 226 of the sensor substrate 227 and the support pillar 224, and is formed for electrical connection. Here, the contact pad 225 is generally formed on the same plane as the reflective pad 215 of the reactant cell 210, and is mainly formed using a metal with high infrared reflectivity such as aluminum, titanium, and gold.

The support pillar 224 is formed between the contact pad 225 and the connection bridge layer 22 connected to the resistor layer 21.

One side of the support pillar 224 is connected to the contact pad 225, and the other side is connected to the connection bridge layer 22. The support pillar 224 is formed of one of titanium (Ti), nickel (Ni), copper (Cu), and aluminum (Al) or an alloy of at least one metal mixed.

The support pillar 224 includes a groove (U) in the center of the pillar. The groove portion of the support pillar 224 is preferably formed so that the thickness of the support pillar 224 is 0.1 μm to 1 μm, but is not necessarily limited thereto. On the other hand, if the thickness of the support pillar 224 is less than 0.1 μm, it becomes difficult to perform the supporting role, and if the thickness of the support pillar 224 exceeds 1 μm, the efficiency of the electrical connection is reduced.

The connection bridge layer 22 includes a connection bridge portion 221a and a connection bridge metal layer 221b.

The connection bridge layer 22 includes a connection bridge portion 221a for connecting the signal layer 226 and the resistor 223a to transmit an electric signal, and a connection bridge metal layer 221b connected to the connection bridge portion 221a. . Additionally, the connection bridge layer 22 may include an insulator 222 to protect the connection bridge portion 221a and the connection bridge metal layer 221b. Here, the connecting bridge portion 221a and the connecting bridge metal layer 221b are made of a metal or conductive ceramic material, such as titanium, chromium, nickel-chromium, or titanium alloy, which has high conductivity and low thermal conductivity.

The resistive layer 21 is connected to the connecting bridge layer 22. The resistive layer 21 includes a resistive layer 223a and a protective layer 223b.

A portion of the resistance layer 223a is connected to the connection bridge 221a and the connection bridge metal layer 221b.

The protective layer 223b is formed to cover the upper and lower surfaces of the resistance layer 223a and is made of an insulating material.

The blocking layer 20 is formed in contact with the resistive layer 21 to block infrared rays. Here, the blocking film layer 20 may include a blocking film 229a and a blocking film protective layer 229b.

The blocking film 229a is formed to have a predetermined distance from the connecting bridge layer 22. Here, the predetermined spacing is preferably between 0.1 μm and 2 μm.

Additionally, the blocking film 229a is formed of the same material as the support pillar 224. That is, the barrier layer 20 may be formed simultaneously at the process step of forming the support pillar 224.

The blocking film 229a may be formed of one of titanium (Ti), nickel (Ni), copper (Cu), and aluminum (Al), or an alloy of at least one metal mixed. The barrier protective layer 229b may be formed of an insulator.

The blocking layer 20 according to the first embodiment is formed on the upper side of the resistor layer 21 and may be formed in a square shape. When the barrier layer 20 is formed in a square shape, it is formed to a thickness of 100 nm or more, and is preferably formed to a thickness capable of reflecting infrared rays in the long wavelength infrared (LWIR) wavelength band of at least 8 to 14 μm.

Meanwhile, the blocking film layer 20 is formed so that the square-shaped upper side of the blocking film layer 20 is at the same height as the upper surface of the insulating layer 222 surrounding one end of the support pillar 224, or the support pillar 224 It may be formed at a height of 0.1 μm to 1 μm higher than the upper surface of the insulating layer 222 surrounding one end of (224). When the blocking layer 20 is formed higher than the upper surface of the insulating layer 222, the infrared blocking rate can be further increased.

The heat conduction layer 228 is located between the resistive layer 21 and the sensor substrate 227. Some areas of the heat conduction layer 228 are connected to the sensor substrate 227. The heat conduction layer 228 allows the absorbed infrared energy to escape to the sensor substrate 227.

Figure 3 is a diagram for explaining the manufacturing process of a reference cell according to the first embodiment of the present invention.

Figure 3(a) shows step S310 of forming the contact pad 225 on the sensor substrate 227.

In step S310, a reflective material is deposited on the sensor substrate 227 and a portion of the area is etched to form a contact pad 225. Here, the contact pad 225 may be formed using a metal material with high infrared reflectance, such as aluminum, titanium, or gold.

The contact pad 225 is formed to be electrically connected to the signal layer 226 of the sensor substrate 227.

Figure 3(b) shows step S320 of forming the heat conduction layer 228 and the resistor layer 21 on the sensor substrate 227 and the contact pad 225.

In step S320, the heat conduction layer 228 is preferentially deposited on the sensor substrate 227 and the contact pad 225, and the resistor layer 21 is deposited on the heat conduction layer 228. Specifically, in step S320, the first protective layer 223b, the resistance layer 223a, and the second protective layer 223b are deposited in that order on the heat conduction layer 228, and the resistance layer 223a and the second protective layer 223b are deposited on the heat conduction layer 228. Both ends of the protective layer 223b are etched.

The heat conduction layer 228 formed in step S320 is formed to have a λ/4 spaced structure with maximum light absorption efficiency. Additionally, the resistance layer 223a is formed for an operation in which resistance changes according to temperature changes.

Figure 3(c) shows step S330 of forming a cavity for forming the support pillar 224.

In step S330, a cavity is formed to electrically connect the signal layer 226 of the sensor substrate 227 and to form a support pillar 224 that supports the structure.

In step S330, cavities are formed through hole patterning and etching at both ends of the second protective layer 223b and the heat conduction layer 228.

Figure 3 (d) shows step S340 of forming the support pillar 224 and the barrier layer 20, and forming the connection bridge layer 22.

Step S340 deposits the support pillar 224 in the already formed cavity and simultaneously forms the barrier layer 20 on the resistor layer 21. That is, the barrier layer 20 is formed simultaneously at the process step of forming the support pillar 224.

When high infrared energy is incident, the infrared energy absorbed by the reference cell 220 cannot be discharged, causing distortion of the image. To prevent this, a blocking film layer 20 is formed at the same time as the support pillar 224.

The blocking layer 20 is formed in contact with the resistive layer 21 to block infrared rays, and is made of the same material as the support pillar 224.

The support pillar 224 and the barrier layer 20 may be formed of one of titanium (Ti), nickel (Ni), copper (Cu), and aluminum (Al) or an alloy of at least one metal mixed.

After the support pillar 224 and the barrier layer 20 are formed, the connection bridge layer 22 is formed in step S340.

The connection bridge layer 22 includes a connection bridge portion 221a for transmitting an electric signal by connecting the signal layer 226 and the resistor 223a, and a connection bridge metal layer 221b connected to the connection bridge portion 221a. is formed in the form Additionally, the connecting bridge layer 22 is formed to include an insulator 222 to protect the connecting bridge portion 221a and the connecting bridge metal layer 221b.

In step S340, the blocking film layer 20 is formed on the upper side of the resistive layer 21 and may be formed in a square shape. When the barrier layer 20 is formed in a square shape, it is formed to have a thickness of 0.1 μm to 1 μm. In addition, the blocking layer 20 is preferably formed to a thickness capable of reflecting infrared rays in the far infrared (LWIR: Long Wavelength InfraRed) wavelength band of at least 8 μm to 14 μm.

Meanwhile, in step S340, the blocking film layer 20 is formed so that the square-shaped upper side of the blocking film layer 20 is at the same height as the upper surface of the insulating layer 222 surrounding one end of the support pillar 224. It can be.

In Figure 3, each step is described as being executed sequentially, but it is not necessarily limited to this. In other words, the steps shown in FIG. 3 may be applied by modifying them or executing one or more steps in parallel, so FIG. 3 is not limited to a time-series order.

4A and 4B are diagrams showing a reference cell of a bolometer infrared sensor according to a second embodiment of the present invention.

FIG. 4A shows a top view of the reference cell 220 of the bolometric infrared sensor according to the second embodiment, and FIG. 4B shows a cross-sectional view of the reference cell 220 of the bolometric infrared sensor according to the second embodiment.

The bolometer infrared sensor according to the second embodiment has a structure to improve output signal uniformity degradation due to unwanted temperature changes in the reference cell due to the high temperature target.

The reference cell 220 according to the second embodiment has the same structure as the reference cell 220 according to the first embodiment shown in FIGS. 2A and 2B, and only the structure of the blocking layer 20 is different, thereby overlapping. The description will be omitted and the differences in the barrier layer 20 will be mainly explained.

The blocking layer 20 is formed in contact with the resistive layer 21 to block infrared rays. Here, the blocking film layer 20 may include a blocking film 229a and a blocking film protective layer 229b.

Additionally, the blocking film 229a is formed of the same material as the support pillar 224. That is, the blocking film 229a can be formed simultaneously at the process step of forming the support pillar 224.

The blocking film 229a may be formed of one of titanium (Ti), nickel (Ni), copper (Cu), and aluminum (Al), or an alloy of at least one metal mixed. The barrier protective layer 229b may be formed of an insulator.

The blocking film layer 20 according to the second embodiment is formed on the upper side of the resistive layer 21 and may be formed in a mesh shape. When the barrier layer 20 is formed in a mesh shape, each grid shape of the mesh shape is formed to have a thickness of 0.1 μm to 1 μm. The mesh-shaped barrier layer 20 has a lower heat capacity compared to the bulk-shaped barrier layer and can emit infrared energy more quickly.

The mesh-shaped barrier layer 20 includes a structure in which a plurality of grids are arranged, the width of the grid pattern may be 0.18 μm to 4 μm, and the width of the space formed between the grids may be 0.18 μm to 4 μm. You can. Here, if the width of the grid pattern of the mesh-shaped blocking film layer 20 is less than 0.18 μm or the width of the space exceeds 4 μm, it is difficult to implement the blocking film and the infrared blocking property may be reduced. If the width of the grid pattern of the mesh-shaped barrier layer 20 exceeds 4 μm or the width of the space is less than 0.18 μm, the aperture ratio of the barrier layer 20 becomes less than a preset threshold and the heat capacity increases.

Meanwhile, the barrier layer 20 is formed so that the mesh-shaped upper surface of the barrier layer 20 is at the same height as the upper surface of the insulating layer 222 surrounding one end of the support pillar 224, or the support pillar 224 It may be formed at a height of 0.1 μm to 1 μm higher than the upper surface of the insulating layer 222 surrounding one end of (224).

Figure 5 is a diagram for explaining the manufacturing process of a reference cell according to a second embodiment of the present invention.

Figure 5(a) shows step S510 of forming the contact pad 225 on the sensor substrate 227.

In step S510, a reflective material is deposited on the sensor substrate 227 and a portion of the area is etched to form a contact pad 225. Here, the contact pad 225 is generally formed on the same plane as the reflective pad 215 of the reactant cell 210, and may be formed using a metal material with high infrared reflectivity such as aluminum, titanium, or gold. .

The contact pad 225 is formed to be electrically connected to the signal layer 226 of the sensor substrate 227.

Figure 5(b) shows step S520 of forming the heat conduction layer 228 and the resistor layer 21 on the sensor substrate 227 and the contact pad 225.

In step S520, the heat conduction layer 228 is preferentially deposited on the sensor substrate 227 and the contact pad 225, and the resistor layer 21 is deposited on the heat conduction layer 228. Specifically, in step S520, the first protective layer 223b, the resistance layer 223a, and the second protective layer 223b are deposited in that order on the heat conduction layer 228, and the resistance layer 223a and the second protective layer 223b are deposited on the heat conduction layer 228. Both ends of the protective layer 223b are etched.

The heat conduction layer 228 formed in step S520 is formed to have a λ/4 spaced structure with maximum light absorption efficiency. Additionally, the resistance layer 223a is formed for an operation in which resistance changes according to temperature changes.

Figure 5(c) shows step S530 of forming a cavity for forming the support pillar 224.

In step S530, a cavity is formed to form a support pillar 224 that supports the electrical connection and structure with the signal layer 226 of the sensor substrate 227.

In step S530, cavities are formed through hole patterning and etching at both ends of the second protective layer 223b and the heat conduction layer 228. Here, etching may be etching using Cl and F- groups.

Figure 5(d) shows step S540 of forming the support pillar 224 and the barrier layer 20, and forming the connection bridge layer 22.

Step S540 deposits the support pillar 224 in the previously formed cavity and simultaneously forms the barrier layer 20 on the resistor layer 21. That is, the barrier layer 20 is formed simultaneously at the process step of forming the support pillar 224.

When high infrared energy is incident, the infrared energy absorbed by the reference cell 220 cannot be discharged, causing distortion of the image. To prevent this, a blocking film layer 20 is formed at the same time as the support pillar 224.

The blocking layer 20 is formed in contact with the resistive layer 21 to block infrared rays, and is made of the same material as the support pillar 224.

The support pillar 224 and the barrier layer 20 may be formed of one of titanium (Ti), nickel (Ni), copper (Cu), and aluminum (Al) or an alloy of at least one metal mixed.

After the support pillar 224 and the barrier layer 20 are formed, the connection bridge layer 22 is formed in step S540.

The connection bridge layer 22 includes a connection bridge portion 221a for transmitting an electric signal by connecting the signal layer 226 and the resistor 223a, and a connection bridge metal layer 221b connected to the connection bridge portion 221a. is formed in the form Additionally, the connecting bridge layer 22 is formed to include an insulator 222 to protect the connecting bridge portion 221a and the connecting bridge metal layer 221b.

In step S540, the blocking film layer 20 is formed on the upper side of the resistive layer 21 and may be formed in a mesh shape.

When the barrier layer 20 is formed in a mesh shape, each grid shape of the mesh shape is formed to have a thickness of 0.1 μm to 1 μm. The mesh-shaped barrier layer 20 has a lower heat capacity compared to the bulk-shaped barrier layer and can emit infrared energy more quickly.

In step S540, the mesh-shaped barrier layer 20 is formed in a structure in which a plurality of grids are arranged, the width of the grid pattern can be formed from 0.18 μm to 4 μm, and the width of the space formed between the grids is It can be formed from 0.18 μm to 4 μm.

Meanwhile, in step S540, the barrier layer 20 is formed so that the mesh-shaped upper surface of the barrier layer 20 is at the same height as the upper surface of the insulating layer 222 surrounding one end of the support pillar 224. It can be.

In Figure 5, each step is described as being executed sequentially, but it is not necessarily limited to this. In other words, the steps shown in FIG. 5 may be applied by modifying them or executing one or more steps in parallel, so FIG. 5 is not limited to a time-series order.

Figures 6a and 6b are diagrams showing a reactant cell of a bolometer infrared sensor according to an embodiment of the present invention.

FIG. 6A shows a plan view of the reactant cell 210 of the bolometric infrared sensor according to this embodiment, and FIG. 6B shows a cross-sectional view of the reactant cell 210 of the bolometric infrared sensor according to this embodiment.

The reactant cell 210 of the bolometer infrared sensor absorbs infrared rays and changes resistance to generate a modulated current signal.

The reactant cell 210 has an absorber layer 30 that absorbs infrared rays, and is designed to have low thermal conductivity to prevent heat absorbed from the absorber layer 30 from being lost to the sensor board 217 containing the signal acquisition circuit, thereby providing thermal isolation. A form including a support pillar 214 that separates the connecting bridge layer 32, the absorber layer 30, and the low window layer 31 from the sensor substrate 217 by about λ/4 to ensure maximum absorption rate. It consists of Here, λ means a wavelength of 8 μm to 14 μm. In order to have maximum absorption efficiency in terms of the light absorption mechanism, it is preferable that the gap between absorption layers in the reflector 215 is implemented as a λ/4 structure (eg, 2 to 3.5 μm).

The resistive layer 31 is connected to the connecting bridge layer 32. The resistive layer 31 includes a resistive layer 213a and a protective layer 213b.

A portion of the resistance layer 213a is connected to the connection bridge 211a and the connection bridge metal layer 211b.

The protective layer 213b is formed to cover the upper and lower surfaces of the resistance layer 213a and is made of an insulating material.

The absorber layer 30 includes an absorption layer 219a that absorbs infrared rays, and an absorption protection layer 219b that serves to electrically insulate or protect the absorption layer 219a from the outside. The absorption layer 219a is implemented in a form that contacts the upper surface of the resistive layer 31, and the absorption protective layer 219b is formed in a form that protects the upper surface of the absorption layer 219a. The absorption protective layer 219b is formed of an insulating material.

The connection bridge layer 32 includes a connection bridge portion 211a and a connection bridge metal layer 211b that electrically connect the resistance layer 213a and the support pillar 214. Additionally, the connecting bridge layer 32 may include an insulator 212 to protect the connecting bridge portion 211a and the connecting bridge metal layer 211b. Here, the connecting bridge portion 211a and the connecting bridge metal layer 211b are made of a metal or conductive ceramic material, such as titanium, chromium, nickel-chromium, or titanium alloy, which has high conductivity and low thermal conductivity.

The support pillar 214 is formed between the reflective pad 215 and the connection bridge layer 32 connected to the resistance layer 213a.

One side of the support pillar 214 is connected to the reflective pad 215, and the other side is connected to the connection bridge layer 32. The support pillar 214 is formed of one of titanium (Ti), nickel (Ni), copper (Cu), and aluminum (Al) or an alloy of at least one metal mixed.

In the reactant cell 210 of FIG. 6, the sacrificial layer, which is the heat conduction layer 218, is removed to form a thermally isolated structure.

Figure 7 is a diagram for explaining the manufacturing process of a reactant cell according to an embodiment of the present invention.

Figure 7(a) shows step S710 of forming the reflective pad 215 on the sensor substrate 217.

In step S710, a reflective material is deposited on the sensor substrate 217 and a portion of the area is etched to form a reflective pad 215. Here, the reflective pad 215 may be formed using a metal material with high infrared reflectance, such as aluminum, titanium, or gold.

The reflective pad 215 is formed to be electrically connected to the signal layer 216 of the sensor substrate 217, and may be formed to reabsorb the transmitted infrared rays.

Figure 7(b) shows step S720 of forming the heat conduction layer 218 and the resistor layer on the sensor substrate 217 and the reflective pad 215.

In step S720, a heat-conducting layer 218 is preferentially deposited on the sensor substrate 217 and the reflective pad 215, and a resistor layer is deposited on the heat-conducting layer 218. Specifically, in step S720, the first protective layer 213b, the resistance layer 213a, and the second protective layer 213b are deposited in that order on the heat conduction layer 218, and the resistance layer 213a and the second protective layer 213b are deposited on the heat conduction layer 218. Both ends of the protective layer 213b are etched.

The heat conduction layer 218 formed in step S720 is formed to have a λ/4 spaced structure with maximum light absorption efficiency. Additionally, the resistance layer 213a is formed for an operation in which resistance changes according to temperature changes.

Figure 7 (c) shows step S730 of forming a cavity for forming the support pillar 214.

In step S730, a cavity is formed to electrically connect the signal layer 216 of the sensor substrate 217 and to form a support pillar 214 that supports the structure.

In step S730, cavities are formed through hole patterning and etching at both ends of the second protective layer 213b and the heat conduction layer 218. Here, etching may be etching using Cl and F- groups.

Figure 7 (d) shows step S740 of forming the support pillar 214 and the connecting bridge layer 32.

Step S740 deposits a support pillar 214 that supports the signal circuit board and electrical connection and structure in the already formed cavity.

The support pillar 214 may be formed of one of titanium (Ti), nickel (Ni), copper (Cu), and aluminum (Al) or an alloy of at least one metal mixed.

After the support pillars 214 are formed, in step S740, a connecting bridge layer 32 is formed to thermally isolate the structure. Here, the connecting bridge layer 32 is formed using a material with low thermal conductivity.

The connection bridge layer 32 includes a connection bridge portion 211a for connecting the signal layer 216 and the resistor 213a to transmit an electric signal, and a connection bridge metal layer 211b connected to the connection bridge portion 211a. is formed in the form Additionally, the connecting bridge layer 32 is formed to include an insulator 212 to protect the connecting bridge portion 211a and the connecting bridge metal layer 211b.

Figure 7(e) shows step S750 of forming the absorption layer 219.

Step S750 forms the absorber layer 30 on the resistor layer 31.

The absorber layer 30 includes an absorption layer 219a that absorbs infrared rays, and an absorption protection layer 219b that serves to electrically insulate or protect the absorption layer 219a from the outside. The absorption layer 219a is implemented in a form that contacts the upper surface of the resistive layer 31, and the absorption protective layer 219b is formed in a form that protects the upper surface of the absorption layer 219a. The absorption protective layer 219b is formed of an insulating material.

Figure 7(f) shows step S760 of removing the heat conductive layer 218 to form a structure for thermal isolation.

Step S760 forms a structure for thermal isolation by removing the sacrificial layer (polyimide), which is the heat conducting layer 218. Step S760 includes a support pillar 214 that separates the connecting bridge layer 32 and the absorber layer 30 from the sensor substrate 217 by about λ/4 to achieve maximum absorption rate by removing the heat conduction layer 218. Forms a structure for thermal isolation.

In Figure 7, each step is described as being executed sequentially, but it is not necessarily limited to this. In other words, the steps shown in FIG. 7 may be applied by modifying and executing one or more steps in parallel, so FIG. 7 is not limited to a time series order.

Figure 8 is a circuit diagram showing a detection circuit in which a reactant cell and a reference cell are connected to a signal acquisition circuit according to an embodiment of the present invention.

The reactant cell 210 is connected to a transistor 240 that determines the bias voltage (Va) and the ground, and the reference cell 220 is connected to another transistor 250 that determines the bias voltage (Vb) and the power line. .

The two transistors 240 and 250 are connected to the negative terminal of the operational amplifier, and this terminal is connected to a capacitor and connected to the output of the operational amplifier.

The positive terminal of the operational amplifier is connected to the reference voltage. The base current (Ia) generated in the reactant cell 210 is canceled by the offset current (Ib) generated in the reference cell.

If the resistance of the reactant cell 210 changes due to the incident infrared rays, the current component flowing through the reactant cell 210 changes, and only this modulated current (ΔI) is integrated into the capacitor 260 and appears as a signal component. .

Figure 9 is an exemplary diagram showing the output of an infrared image using a bolometer infrared sensor according to an embodiment of the present invention.

Figure 9(a) shows an infrared image output by a general bolometer infrared sensor.

Figure 9(b) shows image noise 900 generated when sunlight is incident on the reference cell of a general bolometer infrared sensor.

When a blocking film layer is formed on the reference cell of a bolometer infrared sensor as in an embodiment of the present invention, an infrared image without image noise can be output, as shown in (c) of FIG. 9.

The above description is merely an exemplary explanation of the technical idea of the embodiments of the present invention, and those skilled in the art can make various modifications and modifications without departing from the essential characteristics of the embodiments of the present invention. Transformation will be possible. Accordingly, the embodiments of the present invention are not intended to limit but to explain the technical idea of the embodiment of the present invention, and the scope of the technical idea of the embodiment of the present invention is not limited by these embodiments. The scope of protection of the embodiments of the present invention should be interpreted in accordance with the claims below, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of rights of the embodiments of the present invention.

10: infrared detector 100: infrared window
200: Infrared sensor 300: Feed through unit
210: reactant cell
31: absorber layer 32: connecting bridge layer
214: support pillar 215: contact pad
217: sensor board
220: Reference cell
21: resistor layer 22: connection bridge layer
224: support pillar 225: contact pad
227: sensor substrate 228: heat conduction layer
229: barrier layer

Claims (11)

In a bolometer infrared sensor to minimize output changes caused by high temperature targets,
A sensor substrate including a signal layer for transmitting electrical signals of a signal acquisition circuit;
a contact pad connected to the signal layer of the sensor substrate and for electrical connection;
a support pillar connected to the contact pad on one side and connected to the connection bridge layer on the other side;
a connection bridge layer connected on one side to the support pillar and on the other side connected to a resistor layer;
a resistive layer connected to the connection bridge layer and having variable resistance depending on temperature;
a blocking film layer formed in contact with the resistive layer to block infrared rays; and
It is located between the resistor layer and the sensor substrate, and includes a heat conduction layer in which a portion of the area is connected to the sensor substrate,
The upper side of the barrier layer is formed at the same height as the upper surface of the insulating layer surrounding one end of the support pillar or 0.1 μm to 1 μm higher than the upper surface of the insulating layer surrounding one end of the support pillar. Bolometric infrared sensor, characterized in that. According to paragraph 1,
The barrier layer is,
A bolometric infrared sensor, characterized in that it is formed in a shape having a predetermined separation distance from the connecting bridge layer. According to paragraph 2,
The barrier layer is,
A bolometric infrared sensor, characterized in that it is formed to have a separation distance between the connecting bridge layer and 0.1 μm to 2 μm. According to paragraph 1,
The barrier layer is,
A bolometric infrared sensor that is formed of the same material as the support pillar and is formed simultaneously in the process step of forming the support pillar. According to paragraph 4,
The barrier layer is,
A bolometric infrared sensor, characterized in that it is formed of one metal of titanium (Ti), nickel (Ni), copper (Cu), and aluminum (Al) or an alloy of at least one metal mixed. According to paragraph 1,
The barrier layer is,
A bolometric infrared sensor, characterized in that it is formed in a square shape or mesh shape on the upper side of the resistive layer. According to clause 6,
The barrier layer is,
When formed in a square shape, it is formed to a thickness of 0.1 μm to 1 μm, and is formed to a thickness that can reflect infrared rays in the far infrared (LWIR: Long Wavelength InfraRed) wavelength band of at least 8 to 14 μm. According to clause 6,
The barrier layer is,
When formed in a mesh shape, a bolometric infrared sensor is characterized in that each grid shape is formed with a thickness of 0.1 μm to 1 μm. According to clause 8,
The barrier layer is,
A bolometric infrared sensor formed in a structure in which a plurality of grids are arranged, the width of the grid pattern is 0.18 μm to 4 μm, and the width of the space formed between the grids is 0.18 μm to 4 μm. . delete According to paragraph 1,
The support pillar is,
A bolometric infrared sensor comprising a groove in the center of the pillar, wherein the groove is formed so that the thickness of the support pillar is 0.1 μm to 1 μm.

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