Infrared detector and method for manufacturing same

Abstract

The present invention relates to an infrared detector in which a first membrane is positioned on a first layer disposed on a lower substrate of the infrared detector and a second membrane is positioned on a second layer disposed on the first layer, the infrared detector comprising: a third membrane in which the first membrane and the second membrane are connected to each other; a leg metal electrode formed below the second membrane; and an anchor metal formed below the second membrane, wherein a cavity is formed between the third membrane and the lower substrate.

Description

Infrared detector and method of manufacturing the same

[0001] The present invention relates to an infrared detector that prevents a decrease in infrared responsiveness due to miniaturization of the infrared detector, and a method for manufacturing the same.

[0002] Infrared thermal imaging cameras are devices that detect Long Wavelength Infrared (LWIR) in the 8μm to 14μm band emitted through Black Body Radiation from any object with temperature and convert it into a thermal image that is visible to the naked eye, and can be classified into two types: cooled and uncooled.

[0003] Cooled infrared thermal imaging cameras typically offer excellent thermal resolution, but because they operate in ultra-low temperature environments below -80°C, they are large and expensive, and are primarily used for special purposes such as military, research and development, and aerospace. Although uncooled infrared thermal imaging cameras have lower thermal resolution compared to cooled models, they are mainly used in commercial products due to their advantages of being able to operate at room temperature, being small, inexpensive, and capable of low-power operation.

[0004] Components of uncooled infrared detectors include thermocouples, thermopiles, pyroelectric detectors, and microbolometers; among these, microbolometers (MBs) are primarily used in commercial infrared thermal imaging cameras because they enable the integration of high-resolution focal plane arrays (FPAs) on semiconductor wafers.

[0005] As the demand for commercialization of infrared thermal imaging cameras based on microbolometer focal plane arrays (MBFPA) increases, continuous innovation in size, weight, and price is required. To this end, miniaturization of microbolometer pixels is currently required. In the past, the pixel size was 50μm × 50μm, but it has now been miniaturized to 8μm × 8μm. As the pixel size decreases, MBFPAs of the same resolution can be integrated onto smaller chips, which can significantly reduce the size, weight, and price of thermal imaging cameras, thereby securing high market competitiveness.

[0006] Microbolometers are MEMS devices that feature a quarter-wavelength resonance structure from the substrate to maximize the absorption of incident far-infrared radiation; therefore, they necessarily include a far-infrared non-sensing component that suspends the device in mid-air. Consequently, there is a technical challenge in that the non-sensing component must be miniaturized along with the size of a single pixel as it becomes smaller. If the non-sensing component is not miniaturized to the same level, the proportion of the non-sensing area increases relatively, leading to a decrease in the Fill Factor. The Fill Factor is the ratio of the infrared-sensing area to the total pixel area; a decrease in this value leads to a decline in infrared responsiveness. Since this negatively affects the sensitivity and performance of thermal imaging cameras, there is a need for technology that reduces the pixel's non-sensing area while maximizing the Fill Factor.

[0007] The present invention aims to solve the problem in which, as the pixel size is miniaturized in conventional infrared detectors, the proportion of non-infrared detection areas such as anchors and legs increases, leading to a decrease in Fill-Factor and consequently a degradation in infrared detection performance.

[0008] The present invention aims to solve the problem in which mechanical stability and the difficulty of the manufacturing process increase, and the reliability of the pixel structure decreases, when non-sensing structures such as anchors and legs are excessively reduced.

[0009] The present invention aims to solve the problem that the manufacturing process of conventional infrared detectors is heavily dependent on process conditions such as etching, deposition, and pattern formation, which increases the complexity of the process.

[0010] The present invention aims to solve the problem where the infrared sensing area decreases and the responsiveness decreases as the Fill-Factor decreases.

[0011] The present invention relates to an infrared detector having a first membrane located on a first layer located on a lower substrate of the infrared detector and a second membrane located on a second layer located on the first layer, wherein the infrared detector comprises: a third membrane having a form in which the first membrane and the second membrane are connected; a leg metal electrode formed on the lower part of the second membrane; and an anchor metal formed on the lower part of the second membrane; and is configured such that a cavity is formed between the third membrane and the lower substrate.

[0012] In addition, the thermistor material is configured to be formed on at least one of the upper and lower surfaces of the third membrane.

[0013] In addition, the thermistor material is composed of at least one of VOx (Vanadium Oxide), a-VOx (Amorphous Vanadium Oxide), TiOx (Titanium Oxide), and a-Si (Amorphous Silicon).

[0014] In addition, a protective layer composed of at least one of SiNx (Silicon Nitride) and SiOx (Silicon Oxide) is formed on at least one of the upper and lower surfaces of the third membrane.

[0015] In addition, a first-layer electrode located on the first layer and a second-layer electrode located on the second layer are formed to electrically connect the first membrane and the second membrane, and the first-layer electrode and the second-layer electrode are configured to be continuously connected.

[0016] In addition, the third membrane is characterized by being formed in a cantilever shape.

[0017] The present invention relates to an infrared detector having a first sacrificial layer located on a first layer on a lower substrate of the infrared detector and a second sacrificial layer located on a second layer on the first layer, wherein the first membrane on the first sacrificial layer and the second membrane on the second sacrificial layer are connected to each other; a third membrane having a connected form; a leg metal electrode formed on the lower part of the second membrane; and an anchor metal formed on the lower part of the second membrane.

[0018] In addition, the first sacrificial layer and the second sacrificial layer are formed so that they can be removed through a MEMS process.

[0019] In addition, the first sacrificial layer and the second sacrificial layer are composed of at least one of polyimide, spin-on carbon, and amorphous carbon.

[0020] In addition, the first sacrificial layer and the second sacrificial layer are formed by at least one of the Chemical Vapor Deposition (CVD) and Spin Coating methods.

[0021] Additionally, the anchor metal is formed within the contact holes of the first sacrificial layer and the second sacrificial layer, and the anchor metal is composed of at least one metal among Al, Ti, TiN, Mo, and W.

[0022] The present invention relates to a method for manufacturing an infrared detector, comprising: a step of forming a first sacrificial layer on a lower substrate of the infrared detector; a step of forming a first membrane on the formed first sacrificial layer; a step of forming a second sacrificial layer on the first sacrificial layer; a step of etching the second sacrificial layer; and a step of forming a third membrane by connecting the second membrane on the second sacrificial layer with the first membrane.

[0023] Additionally, the first sacrificial layer formation step; and the second sacrificial layer formation step; further include a step in which the first sacrificial layer and the second sacrificial layer are formed from at least one of polyimide, spin-on carbon, and amorphous carbon.

[0024] Additionally, the membrane forming step further includes a step of including a metal electrode so that the second membrane and the first membrane can be continuously connected.

[0025] The present invention can provide the effect of increasing the Fill-Factor while overcoming the reduction limit of anchors and legs, which are non-sensing structures within the pixel, by configuring a continuous membrane that detects far-infrared rays across a first sacrificial layer and a second sacrificial layer.

[0026] The present invention can maximize the far-infrared detection area through a continuously configured membrane without excessive reduction of the far-infrared non-detection area, thereby providing the effect of preventing a decrease in detection performance compared to existing technology.

[0027] The present invention is designed to maximize the infrared detection area regardless of process conditions, thereby providing the effect of efficiently miniaturizing the infrared detector.

[0028] Figure 1a is a diagram illustrating the general structure of a microbolometer, which is an uncooled infrared detector.

[0029] Figure 1b is a diagram illustrating the operating principle of infrared detection of a microbolometer.

[0030] Figure 2a is a diagram illustrating the problem that occurs when the size of the anchor is reduced.

[0031] FIG. 2b is a diagram illustrating an example of actual pixel miniaturization in which the infrared non-detection area by the anchor becomes relatively wider when the pixel is miniaturized.

[0032] Figure 3a is a diagram illustrating the influence of infrared reactivity according to the leg structure ratio.

[0033] FIG. 3b is a diagram illustrating an example of actual pixel miniaturization in which the infrared non-detection area becomes relatively wider when the pixel is miniaturized.

[0034] FIG. 4 is a drawing showing an example of a continuous dispersed arrangement of membranes according to the present invention.

[0035] FIG. 5 is a drawing showing a projection of a continuous dispersed arrangement of membranes according to the present invention.

[0036] FIG. 6a is a diagram illustrating the current flow inside an infrared detector according to one embodiment of the present invention.

[0037] FIG. 6b is a diagram illustrating the entire current path and a partial current path of a membrane according to one embodiment of the present invention.

[0038] FIG. 7a is a diagram illustrating the thermal path inside an infrared detector in a high vacuum environment according to one embodiment of the present invention.

[0039] FIG. 7b is a drawing illustrating a detailed example of heat flow in a cross-section of an infrared detector according to one embodiment of the present invention.

[0040] FIG. 8 is a drawing for explaining a process for manufacturing an infrared detector having a wing-shaped membrane distributed to have continuity in a first layer and a second layer according to an embodiment of the present invention.

[0041] FIG. 9 is a drawing illustrating a process for manufacturing an infrared detector having a wing-shaped membrane according to a first embodiment of the present invention.

[0042] FIG. 10 is a drawing for explaining a process for manufacturing an infrared detector having a wing-shaped membrane according to a second embodiment of the present invention.

[0043] FIG. 11 is a drawing for explaining a process for manufacturing an infrared detector having a wing-shaped membrane according to a third embodiment of the present invention.

[0044] FIG. 12 is a drawing for explaining a process for manufacturing an infrared detector having a wing-shaped membrane according to a fourth embodiment of the present invention.

[0045] Specific details of the embodiments are included in the detailed description and drawings.

[0046] The advantages and features of the present invention and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below but may be implemented in various different forms. These embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims. Throughout the specification, the same reference numerals refer to the same components.

[0047] Figs. 1a, 1b

[0048] Figure 1a is a diagram illustrating the structure of a microbolometer, which is an uncooled infrared detector. Figure 1b is a diagram illustrating the operating principle of infrared detection by the microbolometer.

[0049] As described, the infrared detector (100) comprises a membrane (110), an anchor metal (120), a leg metal electrode (130), and a reflector (140). Specifically, the membrane (110) comprises a thermistor (111) and an IR absorption layer (112).

[0050] According to the present invention, the membrane (110) absorbs long-wave infrared (LWIR, 10) and converts it into thermal energy, and the resistance of the thermistor (111) changes due to the generated heat. That is, in the infrared detector (100), the membrane (110) corresponds to the region where the long-wave infrared is detected. Generally, the thermistor (111) is composed of a material that has a large change in resistance with temperature change, such as VOx (Vanadium Oxide), a-VOx (Amorphous Vanadium Oxide), a-Si (Amorphous Silicon), and TiOx (Titanium Oxide). That is, the thermistor (111) is a temperature-sensitive resistor and has the characteristic that its electrical resistance value changes according to temperature change. Specifically, since the material of the thermistor (111) has semiconductor characteristics, electron mobility increases as the temperature increases. That is, as infrared rays are absorbed and converted into heat by the infrared absorption layer (112) of the membrane (110), the electrical resistance of the thermistor (111) decreases, and the lower substrate (20) can detect the change in resistance and calculate the intensity of infrared rays emitted by the subject (black body) according to temperature.

[0051] According to the present invention, the infrared detector (100) includes a leg metal electrode (130). Specifically, the leg metal electrode (130) is a structure that supports the membrane (110) and can perform the role of transmitting electrical signals and heat flow. That is, in the infrared detector (100), the leg metal electrode (130) corresponds to an area that does not detect far-infrared rays. In addition, the leg metal electrode (130) can provide a path for the flow of current and can perform the role of transmitting a resistance change generated in the membrane (110) as a signal. In addition, the leg metal electrode (130) may be designed to limit the heat flow of the infrared detector (100) so that the detected heat is not rapidly released to the outside.

[0052] According to the present invention, the infrared detector (100) includes an anchor metal (120). Specifically, the anchor metal (120) corresponds to a structure of a support column that fixes the leg metal electrode (130) and the reflector (140), and simultaneously serves as a connecting part that electrically and thermally connects the lower substrate (20) and the infrared detector. That is, in the infrared detector (100), the anchor metal (120) corresponds to an area that does not detect far-infrared rays.

[0053] According to the present invention, the infrared detector (100) includes a reflector (140). Specifically, the reflector (140) is positioned below the membrane (110) and can perform the role of reflecting far-infrared rays (10) back to the membrane (110). That is, the infrared detector (100) can increase the infrared absorption rate through multiple reflections of far-infrared rays (10) via the reflector (140). In addition, the infrared detector (100) has a λ / 4 cavity resonance structure for the far-infrared wavelength band, with the height between the membrane (110) and the reflector (140) fixed at 2.0 μm or more and 2.5 μm or less. Due to the λ / 4 cavity resonance structure, the infrared detector (100) can induce a resonance effect for the incident far-infrared signal, thereby maximizing the absorption efficiency of the far-infrared rays (10).

[0054] As described above, when the membrane (110) absorbs far-infrared rays (10), the absorbed infrared rays are converted into heat in the infrared absorption layer (112) material of the membrane (110), thereby increasing the temperature of the thermistor (111) material of the membrane (110). As the temperature of the thermistor (111) material increases, the resistance of the thermistor (111) changes, and an electrical signal can be generated. At this time, some of the far-infrared rays (10) may pass through the membrane (110) and reach the reflector (140), and the reflector (140) can reflect the transmitted far-infrared rays (10) back to the membrane (110) to increase absorption efficiency through multiple reflection. Additionally, the electrical signal generated in the thermistor (111) can be transmitted to the lower substrate (20) through the leg metal electrode (130). Afterwards, the signal transmitted to the lower substrate (20) can be converted into a thermal image from a thermal imaging camera.

[0055] Fig. 2a

[0056] FIG. 2a is a drawing for explaining the problem that occurs when the size of the anchor according to the present invention is reduced.

[0057] According to the present invention, the infrared detector (100) has a λ / 4 cavity resonance structure in which the height between the membrane (110) and the reflector (140) is set to be 2.0 μm or more and 2.5 μm or less, so the height of the anchor metal (120) is fixed to be 2.0 μm or more and 2.5 μm or less regardless of the pixel size of the infrared detector (100). In this case, the planar size of the anchor metal (120) is determined by an aspect ratio defined as the ratio of the height (T) and width (W) of the fixed anchor, so there is a limitation on reducing the planar size of the anchor metal (120) depending on the semiconductor process conditions and equipment environment. That is, when the pixel size of the infrared detector (100) becomes smaller, the area occupied by the anchor metal (120) within the infrared detector (100) becomes relatively larger, so the area of ​​the membrane (110) that receives far-infrared rays (10) becomes narrower. Consequently, a problem arises in which the responsiveness of the far-infrared rays (10) is reduced due to a decrease in the Fill Factor.

[0058] According to the present invention, the Fill Factor (%) is a value obtained by dividing the far-infrared detection area by the entire pixel area of ​​the infrared detector (100), and represents a value proportional to the infrared responsiveness of the infrared detector (100) (infrared responsiveness ∝ Fill Factor). In order to minimize the degradation of infrared responsiveness performance due to pixel miniaturization, the Fill Factor (%) must be maintained at the same level as before. Therefore, as the pixel of the infrared detector (100) becomes smaller, the size of the anchor metal (120) must also be reduced; however, if the size of the anchor metal (120) becomes excessively small, it may cause structural problems.

[0059] As illustrated in FIG. 2a, the aspect ratio is the value obtained by dividing the height (T) of the anchor by the width (W) of the anchor. If the width (W) of the anchor metal (120) decreases as the pixel of the infrared detector (100) decreases, the area receiving far-infrared rays (10) can be relatively widened. However, if the width (W) of the anchor metal (120) becomes excessively small, an anchor crack (120-2) may occur. Specifically, if miniaturization is attempted by reducing the width (W) of the anchor, the aspect ratio of the anchor metal (120) increases, and thus stress concentration may occur between the bottom part of the anchor metal (120) and the membrane (110). Such stress can cause cracks in the structure of the anchor metal (120), thereby reducing mechanical stability. Accordingly, the anchor metal (120) that has cracked cannot stably support the membrane (110), and if used for a long period after manufacturing, the crack may progress further and the anchor metal (120) may be completely damaged, which may lead to a decrease in the reliability of the infrared detector.

[0060] According to the present invention, if the width (W) of the anchor metal (120) becomes excessively small, an anchor open (120-1) may occur in the anchor metal (120). Specifically, the anchor open (120-1) indicates a state in which the anchor metal (120) does not come into complete contact with the lower substrate (20), and as a result, the electrical and mechanical connection between the membrane (110) and the lower substrate (20) may be severed. Consequently, the anchor metal (120) is unable to transmit the signal generated from the membrane (110) to the lower substrate (20), and this may lead to an increase in production costs due to a failure of the infrared detector.

[0061] Fig. 2b

[0062] FIG. 2b is a diagram illustrating an example of actual pixel miniaturization in which the infrared non-detection area by the anchor becomes relatively wider when the pixel according to the present invention is miniaturized.

[0063] As illustrated in (a) of FIG. 2b, the membrane (110) can be divided into an infrared sensing area (110-1), which is an area capable of detecting far-infrared rays (10), and an infrared non-sensing area (110-2), which is an area capable of detecting far-infrared rays (10). As previously mentioned, in the case of a conventional infrared detector (100), as the pixel size becomes smaller, the proportion of the infrared non-sensing area (110-2) increases relatively.

[0064] As shown in (b) of FIG. 2b, in the case of ideal pixel miniaturization, the infrared sensing area (110-1) occupies a high proportion of the total pixel area, so it can be seen that the Fill-Factor (D1) is high. That is, ideal pixel miniaturization with a high Fill-Factor (D1) must be implemented, but as mentioned above, a problem arises due to the size of the anchor metal (120) becoming smaller.

[0065] As shown in (c) of FIG. 2b, in the case of actual pixel miniaturization, compared to the fill factor before pixel miniaturization, the infrared sensing area (110-1) occupies a low proportion of the total pixel area, so it can be seen that the Fill-Factor (D2) appears relatively low. That is, it can be seen that the Fill-Factor (D2) in actual pixel miniaturization shows a relatively lower value than the Fill-Factor (D1) in ideal pixel miniaturization.

[0066] Fig. 3a

[0067] FIG. 3a is a drawing for explaining the problem that occurs when the length of the leg according to the present invention is shortened.

[0068] According to the present invention, when the pixels of the infrared detector (100) become smaller, the area of ​​the far-infrared light receiving region itself inevitably decreases, and thus the infrared responsiveness decreases (infrared responsiveness ∝ pixel area). That is, the infrared detection region (110-1) decreases from the total pixel area, and thus the infrared responsiveness of the infrared detector (100) decreases. Furthermore, since the infrared responsiveness of the infrared detector (100) is proportional to the structural ratio (=L / W) of the leg metal electrode (130), which is the length (L) of the leg metal electrode (130) divided by the width (W) of the leg metal electrode (130), in order to prevent the decrease in infrared responsiveness due to the miniaturization of the pixels of the infrared detector (100), the width of the leg metal electrode (130) must be reduced and the length increased.

[0069] As illustrated in FIG. 3a(b), the influence of the leg structure ratio on infrared reactivity according to the structure of the leg metal electrode (130) is explained. When the length (L) is reduced by half and the width (W) of the leg metal electrode (130) is increased by a factor of two, consequently, the leg metal electrode (130) structure ratio is reduced by a factor of one-fourth compared to FIG. 3a(a), and thus the infrared reactivity is also reduced by a factor of one-fourth.

[0070] Fig. 3b

[0071] FIG. 3b is a diagram illustrating an example of actual pixel miniaturization in which the infrared non-detection area by the leg becomes relatively wider when the pixel according to the present invention is miniaturized.

[0072] As illustrated, (b) of FIG. 3b represents the case of ideal pixel miniaturization. However, in reality, when the size of the pixel of the infrared detector (100) is reduced, the space available to extend the leg metal electrode (130) is limited, and the lithographic minimum linewidth acts as a limiting factor when adjusting the width (W) or length (L) of the leg metal electrode (130) in the MEMS (Micro-Electro-Mechanical Systems) process. Therefore, due to process limitations, there is a realistic problem in that the leg metal electrode (130) cannot be designed to be too thin and long. That is, since the infrared detection area (110-1) resulting from actual pixel miniaturization is reduced compared to the infrared detection area (110-1) resulting from ideal pixel miniaturization, it can be intuitively confirmed that the Fill-Factor (D3) in actual pixel miniaturization shows a very low value compared to the Fill-Factor (D1) in ideal pixel miniaturization.

[0073] Fig. 4

[0074] FIG. 4 is a drawing showing an example of a continuous dispersed arrangement of membranes according to the present invention.

[0075] Conventional microbolometer cross-section

[0076] As illustrated in FIG. 4(a), the cross-section of the conventional infrared detector (100) is structured such that a membrane (110) is positioned on a reflector (140) on a lower substrate (20). Additionally, leg metal electrodes (130) and anchor metals (120) corresponding to infrared non-detecting regions (110-2) are positioned on both sides of the membrane (110). That is, in the structure of FIG. 4(a), the region where only the membrane (110) is positioned, excluding the infrared non-detecting regions (110-2) on both sides, becomes the infrared detection region (110-1), thus resulting in a structure where a reduction in Fill-Factor occurs due to pixel miniaturization.

[0077] Microbolometer cross-section according to the present invention

[0078] As illustrated in FIG. 4(b), the membrane (110) structure according to the present invention represents a structure that maximizes the Fill-Factor by extending a portion of the membrane (110) on top of the leg metal electrode (130) and anchor metal (120) corresponding to the existing infrared non-sensing region (110-2). Specifically, the membrane (110) structure according to the present invention can eliminate the influence of the infrared non-sensing region (110-2) due to pixel miniaturization by configuring the sacrificial layer (31, 33) into two layers (hereinafter referred to as the first sacrificial layer and the second sacrificial layer) during the MEMS semiconductor process described later, so that the membrane (110) is distributed and arranged to have continuity between the first and second layers. That is, the membrane (110) structure according to the present invention can be designed to have a wing structure having continuity between the first and second layers through a MEMS semiconductor process using a first sacrificial layer (31) and a second sacrificial layer (33), so that the Fill-Factor of the infrared detector (100) can be designed to have a value greater than a threshold value close to 100%.

[0079] Fig. 5

[0080] FIG. 5 is a drawing showing a projection of a continuous dispersed arrangement of membranes according to the present invention.

[0081] As shown in FIG. 5(a), the upper surface of the infrared detector (100) according to the present invention is designed so that the membrane (110) is distributed to have continuity between the first and second layers, and thus the Fill-Factor is designed to have a value greater than a threshold value close to 100%. That is, it can be seen that most of the area of ​​the entire pixel area of ​​the infrared detector (100) according to the present invention becomes an infrared detection area (110-1).

[0082] As shown in FIG. 5(b), when the upper surface of the infrared detector (100) according to the present invention is projected, it can be seen that a leg metal electrode (130) and an anchor metal (120) corresponding to the existing infrared non-detecting area (110-2) are located on both sides of the membrane (110).

[0083] However, regardless of whether the leg metal electrode (130) and anchor metal (120) corresponding to the existing infrared non-detecting area (110-2) are located on both sides of the membrane (110), the infrared detector (100) according to the present invention is designed so that the Fill-Factor can still have a value greater than a threshold of 100% because the membrane (110) has a wing shape distributed so as to have continuity in the first and second layers.

[0084] Fig. 6a

[0085] FIG. 6a is a diagram illustrating the current flow of an infrared detector according to one embodiment of the present invention.

[0086] As described, the current flow of the infrared detector (100) is such that the first anchor (120-①) is the starting point of the current flow, current flows into the first anchor (120-①) from an external circuit, and the current can be transmitted to the first leg (130-②). Subsequently, the current moves along the first leg (130-②) to the membrane (110-③), and current can flow according to the resistance change generated by infrared detection inside the membrane (110). In this process, the membrane (110-③) can detect infrared energy as an electrical signal.

[0087] Subsequently, the current passing through the membrane (110-③) moves along the second leg (130-④) to the second anchor (120-⑤), and the current can be transmitted to the lower substrate (20) through the second anchor (120-⑤). That is, the infrared detector (100) according to the present invention has a wing shape in which the membrane (110) is distributed to have continuity in the first and second layers, so that the Fill-Factor can still have a value greater than a threshold value close to 100%, and thus the range for detecting infrared rays is increased, thereby providing an effect of increasing the electrical signal due to the increase in infrared responsiveness.

[0088] Fig. 6b

[0089] FIG. 6b is a diagram illustrating the entire current path and a partial current path of a membrane according to one embodiment of the present invention.

[0090] As described, the membrane (110) of the present invention includes a protective layer (201), an electrode (202), a thermistor (111), and an insulating layer (203). At this time, the current flow path of the infrared detector (100) can be divided into two ways. Specifically, when the upper and lower parts of the membrane (110) are connected in a continuous structure, the current passes through the entire area of ​​the membrane (110). In FIG. 6b (a), the current introduced through leg #1 (130-①) can move through the electrode (202), move through the thermistor (111), pass through both the upper and lower parts of the membrane (110), and then be output to leg #2 (130-②) through the electrode (202). In this case, the current flows uniformly across the entire area of ​​the membrane (110), thereby minimizing noise in terms of flicker noise and securing a higher level of temperature resolution.

[0091] As illustrated in FIG. 6b (b), in the case where only the lower region of the membrane (110) is used as a current path, current can be introduced through leg #1 (130-①), pass only through the lower region of the membrane (110), and then be output through leg #2 (130-②). FIG. 6b (b) has the advantage of increasing the stability of current flow because the current flow path is limited only to the lower membrane, but it has the disadvantage of relatively degraded noise performance compared to FIG. 6b (a) in terms of the flicker noise described above. However, since the present invention can utilize both the current flow of FIG. 6b (a) and FIG. 6b (b), the current flow of FIG. 6b (a) can be adopted depending on the application field and purpose of use of the uncooled infrared thermal imaging camera.

[0092] Fig. 7a

[0093] FIG. 7a is a diagram illustrating the thermal path of a membrane according to one embodiment of the present invention.

[0094] As described, the thermal flow of the infrared detector (100) according to the present invention can move from the membrane (110-①) to the legs (130-②) on both sides to the anchors (120-③) on both sides.

[0095] Fig. 7b

[0096] FIG. 7b is a diagram illustrating an example of heat flow of a membrane in a high vacuum environment according to one embodiment of the present invention.

[0097] As illustrated in FIG. 7b (a), when far-infrared rays (10) are incident on an infrared detector (100) according to the present invention in a high vacuum environment, the membrane (110) in the form of a continuous upper and lower membrane can absorb the far-infrared rays (10) and convert them into heat. At this time, as shown in FIG. 7b (b), the infrared absorbed heat converted in the membrane (110) can move from the membrane (110-①) to the legs (130-②) on both sides and to the anchors (120-③) on both sides.

[0098] Fig. 8, Fig. 9, Fig. 10, Fig. 11, Fig. 12,

[0099] FIG. 8 is a diagram illustrating a process for manufacturing an infrared detector having a wing-shaped membrane distributed to have continuity in a first layer and a second layer according to one embodiment of the present invention. FIG. 9 is a diagram illustrating a process for manufacturing an infrared detector having a wing-shaped membrane according to a first embodiment of the present invention. FIG. 10 is a diagram illustrating a process for manufacturing an infrared detector having a wing-shaped membrane according to a second embodiment of the present invention. FIG. 11 is a diagram illustrating a process for manufacturing an infrared detector having a wing-shaped membrane according to a third embodiment of the present invention. FIG. 12 is a diagram illustrating a process for manufacturing an infrared detector having a wing-shaped membrane according to a fourth embodiment of the present invention.

[0100] Step of applying or depositing a first sacrificial layer on a first substrate including a lower substrate and a reflective layer (S100)

[0101] As described, the method for manufacturing an infrared detector (100) according to the present invention may include a step (S100) of applying or depositing a first sacrificial layer on a first substrate comprising a lower substrate and a reflective layer. As shown in 9-1 of FIG. 9, the first substrate (30) may include a lower substrate (20) and a reflector (140). At this time, a first sacrificial layer (31) may be applied or deposited on the first substrate (30). Here, the first sacrificial layer (Sacrificial Layer, 31) may refer to a layer temporarily used to fabricate a specific structure or to form a desired space, such as a cavity or gap, in semiconductor and MEMS (Micro-Electro-Mechanical Systems) processes. In the infrared detector (100), a sacrificial layer may be used to form a space such as a λ / 4 cavity required between the membrane (110) and the first substrate (30), and by depositing the first sacrificial layer (31) to a desired thickness and then removing it, a structure can be created in which the membrane (110) floats above the substrate. Additionally, the first sacrificial layer (31) can achieve the thickness required to form a λ / 4 resonance structure in the infrared detector (100) of the present invention. Below, 10-1 shown in FIG. 10, 11-1 shown in FIG. 11, and 12-1 shown in FIG. 12 may also apply or deposit the first sacrificial layer (31) on the first substrate (30).

[0102] According to one embodiment of the present invention, the first sacrificial layer (31) may be made of polyimide or a carbon-based material. Specifically, polyimide is a polymer material that is thermally stable and has excellent insulating properties. When used as the first sacrificial layer (31), it provides high thermal resistance and uniform coating ability, and can be removed using plasma etching or wet chemical etching. Additionally, carbon-based materials are generally formed by a spin-on carbon (SOC) coating method or an amorphous carbon chemical vapor deposition (CVD) method. They can maintain their shape even at high temperatures and can be easily removed mainly through dry etching, such as O2 (oxygen) plasma etching.

[0103] Anchor Post Example

[0104] As illustrated in FIG. 11, the anchor post (121) is a structure of a MEMS (Micro-Electro-Mechanical Systems) device, such as an infrared detector (100), and can form a physical connection between the membrane (110) and the lower substrate (20). Additionally, the anchor post (121) is mainly composed of metal materials such as Al (aluminum), Ti (titanium), TiN (titanium nitride), Mo (molybdenum), and W (tungsten), and a first sacrificial layer (31) composed of polyimide or carbon-based material may be formed before the anchor post (121) is formed.

[0105] According to one embodiment of the present invention, by forming an anchor post (121), the height of the anchor metal (120) can be lowered and the width of the anchor metal (120) can be reduced. By reducing the height (T) of the anchor metal (120) and securing a process margin for aspect ratio, the anchor width (W) can be further reduced. The infrared non-detecting area (110-2) is reduced, allowing the Fill-Factor to increase. However, the wing-shaped membrane (110) distributed to have continuity in the first and second layers of the present invention may provide a Fill-Factor value greater than a critical value regardless of the infrared non-detecting area (110-2) resulting from the reduction in the width of the anchor metal (120).

[0106] Example of a stair structure

[0107] As illustrated in FIG. 12, the infrared detector (100) of the present invention may form a stepped structure by means of a metal layer (141) below the detection circuit. Adjusting the height of the anchor metal (120) through the stepped structure contributes to reducing the width of the anchor metal (120), similar to the anchor post described above, thereby reducing the infrared non-detection area (110-2) and allowing the Fill-Factor to increase. However, the wing-shaped membrane (110) distributed to have continuity in the first and second layers of the present invention may provide a Fill-Factor value greater than a critical threshold, regardless of the infrared non-detection area (110-2) resulting from the reduction in the width of the anchor metal (120).

[0108] As illustrated in FIG. 12-1, the lower substrate (20) of the present invention can be etched to form a lower metal layer (141) of the detection circuit, and the lower metal layer (141) of the detection circuit can be utilized as a reflector (140).

[0109] Anchor formation step (S110) on the first substrate

[0110] As illustrated, the method for manufacturing an infrared detector (100) according to the present invention may include an anchor formation step (S110) on a first substrate. As illustrated in FIGS. 9-2, FIGS. 10-2, FIGS. 11-2 and FIGS. 12-2, the first substrate (30) may include a lower substrate (20) and a reflector (140), and a first sacrificial layer (31) may be formed on the first substrate (30). At this time, an anchor metal (120) may be formed on the first substrate (30). Specifically, an area where an anchor is to be formed on the first sacrificial layer (31) may be masked through lithography, a portion of the first sacrificial layer (31) may be removed using an etching process, and a pattern may be formed at a location where the anchor metal (120) is to be placed. At this time, the anchor metal (120) may be made of a metal that has excellent physical strength or provides high electrical and thermal conductivity, such as Al, Ti, TiN, Mo, W, etc.

[0111] Step of forming a leg connected to an anchor and a first-layer electrode (S120)

[0112] As described, the method for manufacturing an infrared detector (100) according to the present invention may include a step (S120) of forming a leg and a first-layer electrode connected to an anchor. Specifically, as illustrated in FIGS. 9-3, FIGS. 10-3, FIGS. 11-3 and FIGS. 12-3, the step (S120) of forming a leg and a first-layer electrode connected to an anchor is a step of forming a leg metal electrode (130) connecting the anchor metal (120) and the membrane (110) and a first-layer electrode (32) for electrical signal transmission, and the leg metal electrode (130) and the first-layer electrode (32) may be made of a metallic material such as Ti or TiN. In addition, the upper and lower protective layers (201) of the leg metal electrode (130) and the first-layer electrode (32) may be made of a dielectric (insulator) composed of SiNx, SiOx, etc. At this time, the leg metal electrode (130) and the first layer electrode (32) material may simultaneously perform the role of an absorption layer that directly absorbs incident far-infrared rays in addition to electrical connection, and the Sheet Resistance of the electrode material may be maintained in a range of 500Ω / □ or less. Here, Sheet Resistance is a value obtained by measuring the electrical resistance of a thin layer, such as a thin film or a conductive film, by area, and may be a value obtained by dividing the resistivity [Ω·cm] of the material by the thickness [cm] of the layer.

[0113] As described, the first layer electrode (32) is used as an initial path for current flow and can be connected via the anchor metal (120) and the leg metal electrode (130). Additionally, the first layer electrode (32) can collect a resistance change signal generated by infrared absorption heat in the infrared detector (100) and transmit the signal in conjunction with the second layer electrode (34) generated in FIG. 9-6.

[0114] Second sacrificial layer application or deposition step (S130)

[0115] As described above, the method for manufacturing an infrared detector (100) according to the present invention may include a second sacrificial layer coating or deposition step (S130). Specifically, Polyimide is a polymer material that is thermally stable and has excellent insulating properties. When used as the first sacrificial layer (31), it provides high thermal resistance and uniform coating ability, and can be removed using plasma etching or wet chemical etching. Additionally, carbon-based materials are generally formed by a Spin on Carbon (SOC) coating method or an Amorphous Carbon (amorphous carbon film) chemical vapor deposition (CVD) method. They can maintain their shape even at high temperatures and can be removed very easily, mainly through dry etching, such as O2 (oxygen) plasma etching.

[0116] According to one embodiment of the present invention, the first sacrificial layer (31) may be utilized to form the lower cavity of the membrane (110) mainly in the steps of FIG. 9-1, FIG. 10-1, FIG. 11-1, and FIG. 12-1. On the other hand, the second sacrificial layer (33) may be utilized to form the upper structure of the membrane (110) mainly in FIG. 9-4, FIG. 10-4, FIG. 11-4, and FIG. 12-4. Additionally, the second sacrificial layer (33) may be utilized to connect the first layer electrode (32) and the second layer electrode (34) mainly in FIG. 9-6, FIG. 10-6, FIG. 11-6, and FIG. 12-6.

[0117] Step of opening the first layer electrode by etching the second sacrificial layer (S140)

[0118] Patterning by reflow method

[0119] As described, the method for manufacturing an infrared detector (100) according to the present invention may include a step (S140) of opening a first-layer electrode by etching a second sacrificial layer. Specifically, as shown in FIG. 9-5, the second sacrificial layer (33) may be etched to expose part or all of the first-layer electrode (32). At this time, the opened portion of the first-layer electrode (32) may become an electrical path that can be connected to the second electrode (34) that is subsequently created.

[0120] As illustrated in FIG. 9-5, the second sacrificial layer (33) can be etched to create a membrane (110) with a uniform and gentle slope and curvature through PR masking and a reflow process. Specifically, after applying PR (Photoresist) onto the second sacrificial layer (33), a PR pattern can be formed through a lithography process. At this time, the PR pattern can be reflowed through heat treatment, and during the reflow process, the PR can be rearranged to form a gentle curvature and slope. Accordingly, the periphery of the first-layer electrode (32) open on the second sacrificial layer (33) can have a smooth curvature and slope. That is, patterning by the reflow method may be suitable for processes requiring a sloped surface or a smooth curvature of the membrane (110).

[0121] PR patterning between 45 and 90 degrees

[0122] As described, the method for manufacturing an infrared detector (100) according to the present invention may include a step (S140) of opening a first-layer electrode by etching a second sacrificial layer. Specifically, as shown in FIG. 10-5, a second sacrificial layer (33) may be etched to expose part or all of the first-layer electrode (32). At this time, the opened portion of the first-layer electrode (32) may become an electrical path that can be connected to a second electrode (34) that is subsequently created.

[0123] As illustrated in FIG. 10-5, a PR pattern can be formed through a lithography process by etching the second sacrificial layer (33). Specifically, the angle of inclination of the PR pattern on the second sacrificial layer (33) can be set to 45 degrees or more and 90 degrees or less to form a gentle slope. That is, PR patterning with an angle of 45 degrees or more and 90 degrees or less is suitable for mass production and may be suitable for processes advantageous for right-angle or vertical patterns. In addition, as illustrated in FIG. 11-5 and FIG. 12-5, even when an anchor post (121) or a metal layer (141) under a detection circuit is formed, the first layer electrode (32) can be opened by applying patterning by a reflow method or PR patterning with an angle of 45 degrees or more and 90 degrees or less.

[0124] Step (S150) for forming a second layer electrode that is electrically connected to a first layer electrode

[0125] As described, the method for manufacturing an infrared detector (100) according to the present invention may include a step (S150) of forming a second electrode that is electrically connected to a first electrode. Specifically, as shown in FIGS. 9-6, 10-6, 11-6 and 12-6, a first electrode (32) and a second electrode (34) may be connected. Accordingly, as the second electrode (34) is connected to the first electrode (32), the infrared detection area (110-1) can be extended to the entire membrane (110). That is, the present invention can provide the effect of increasing the Fill-Factor through the step (S150) of forming a second electrode that is electrically connected to a first electrode. In addition, the electrode material of the leg metal electrode (130) and the membrane (110) is a metal material such as Ti or TiN, and has a Sheet Resistance that is the same or similar to that of the lower electrode, and can be adjusted to a range of 500Ω / □ or less to maintain the far-infrared absorption and signal transmission performance of the infrared detector (100).

[0126] Step of forming a cantilever structure after depositing thermistor material on the first layer electrode and the second layer electrode (S160)

[0127] As described, the method for manufacturing an infrared detector (100) according to the present invention may include a step (S160) of forming a cantilever structure after depositing a thermistor material, a far-infrared absorbing material, and an upper protective layer on a first-layer electrode and a second-layer electrode. Specifically, as shown in FIGS. 9-6, 10-6, 11-6 and 12-6, a thermistor material may be deposited on a first-layer electrode (32) and a second-layer electrode (34).

[0128] According to one embodiment of the present invention, the thermistor material is made of a metal oxide (Thermistor Oxide Material) such as TiOx (Titanium Oxide), VOx (Vanadium Oxide), and a-VOx (Amorphous Vanadium Oxide), and a resistive dielectric material such as a-Si (Amorphous Silicon). In addition, the cantilever structure formation step (S160), which involves depositing a far-infrared absorption layer and a membrane upper protective layer after depositing the thermistor material on the first electrode and the second electrode, can deposit the thermistor material on the first electrode (32) and the second electrode (34) by utilizing sputtering, CVD (Chemical Vapor Deposition), and ALD (Atomic Layer Deposition) methods.

[0129] Additionally, the step of forming a cantilever structure (S160) after depositing a thermistor material on the first and second electrodes may remove unnecessary parts through a photolithography process and perform patterning so that the thermistor is aligned with the electrodes. Specifically, by depositing a thermistor material on the first electrode (32) and the second electrode (34), the infrared detector (100) of the present invention can convert temperature changes into electrical signals when infrared is detected, and can efficiently convert infrared energy into electrical signals.

[0130] That is, when infrared rays are incident on the membrane (110), the infrared absorption heat converted through the infrared absorbing material included in the membrane stacking structure is transferred to the thermistor, and the resistance value changes, so an electrical signal can be generated according to the infrared intensity. At this time, the material that absorbs far-infrared rays is a thin metallic film such as TiN (Titanium Oxide) or NiCr (Nichrome) and a relatively thick dielectric material such as SiNx (Silicon Nitride) or SiOx (Silicon Oxide).

[0131] According to one embodiment of the present invention, after depositing a thermistor material on a first-layer electrode (32) and a second-layer electrode (34), a cantilever shape, which is a suspended structure, can be formed using a membrane structure. Accordingly, the infrared detector (100) of the present invention can minimize heat conduction loss and improve temperature sensing sensitivity through the cantilever structure. In addition, to protect the thermistor material deposited on the first-layer electrode (32) and the second-layer electrode (34), additional protective layers may be formed on the upper and lower portions of the membrane (110). Specifically, protective layers on the upper and lower portions of the membrane (110) may be formed using materials such as SiNx (Silicon Nitride) and SiOx (Silicon Oxide) to increase resistance to temperature changes, improve durability, and prevent unnecessary oxidation and damage. At this time, the membrane (110) may be etched to realize the cantilever structure.

[0132] Step for removing the first and second sacrifice layers (S170)

[0133] As described, the method for manufacturing an infrared detector (100) according to the present invention may include a step (S170) of removing a first sacrificial layer and a second sacrificial layer. Specifically, as shown in FIGS. 9-6, 10-6, 11-6 and 12-6, the first sacrificial layer (31) and the second sacrificial layer (33) can be removed to form a cavity and realize a membrane (110) floating structure. That is, by removing the first sacrificial layer (31) and the second sacrificial layer (33), a cavity is formed between the lower substrate (20) and the membrane (110) of the infrared detector (100) according to the present invention, thereby physically separating the membrane (110) from the lower substrate (20) and having a suspended structure. In addition, as a cavity is formed, heat exchange between the membrane (110) and the external environment is minimized in a high vacuum environment, and as a result, when infrared rays are absorbed by the membrane, a greater temperature change occurs, which improves the change in resistance of the thermistor and provides the effect of improving infrared responsiveness.

[0134] According to one embodiment of the present invention, the removal of the first sacrificial layer (31) and the second sacrificial layer (33) can be achieved using an O₂ plasma ashing method. Specifically, the O₂ plasma ashing method is a method of chemically decomposing and removing the first sacrificial layer (31) and the second sacrificial layer (33) using oxygen (O₂) plasma. Since the sacrificial layer is mainly a polyimide or carbon-based material, it can be removed in a gaseous state by reacting with oxygen.

[0135] That is, as the first sacrificial layer (31) and the second sacrificial layer (33) below the membrane (110) are removed, a cavity is created between the lower substrate (20) and the membrane (110), and the size of the cavity can be determined according to the thickness of the first sacrificial layer (31) and the second sacrificial layer (33). Additionally, the membrane (110) is fixed only by the anchor metal (120) and the leg metal electrode (130), and the center can be completely floating. Accordingly, the infrared detector (100) blocks heat transfer with the surrounding atmosphere in a high vacuum environment and heat transfer due to direct contact with the lower substrate, thereby limiting heat flow only through the leg, so that the temperature change occurring after infrared absorption can be measured more precisely.

[0136] The scope of the present invention is not limited to the embodiments described above but may be implemented in various forms of embodiments within the scope of the appended claims. It is deemed that the scope of the claims of the present invention includes various modifications that are possible by anyone with ordinary knowledge in the technical field to which the invention pertains, without departing from the essence of the invention claimed in the claims.

[0137] [Explanation of the symbol]

[0138] 20: Lower substrate

[0139] 31: 1st Sacrifice Layer

[0140] 33: Second Sacrifice Layer

[0141] 100: Infrared detector

[0142] 110: Membrane

[0143] S100: Step of applying or depositing a first sacrificial layer on a first substrate including a lower substrate and a reflective layer

[0144] S110: Anchor formation step on the first substrate

[0145] S120: Step of forming a leg connected to an anchor and a first-layer electrode

[0146] S130: Second sacrificial layer application or deposition step

[0147] S140: Step of opening the first layer electrode by etching the second sacrificial layer

[0148] S150: A method for manufacturing an infrared detector involves a step of forming a second-layer electrode electrically connected to a first-layer electrode.

[0149] S160: Step of forming a cantilever structure after depositing a thermistor material, a far-infrared absorbing material, and an upper protective layer on the first-layer electrode and the second-layer electrode.

[0150] S170: Step to remove the first and second victim layers

Claims

1. In the infrared detector having a first membrane located on a first layer located on a lower substrate of the infrared detector and a second membrane located on a second layer located on the first layer, the infrared detector having a first membrane formed thereon. A third membrane having a form in which the first membrane and the second membrane are connected; A leg metal electrode formed on the lower part of the second membrane; and Anchor metal formed on the lower part of the second membrane; comprising Configured so that a cavity is formed between the third membrane and the lower substrate, Infrared detector.

2. In Paragraph 1, The thermistor material is configured to be formed on at least one of the upper and lower membranes of the third membrane, or the thermistor material is continuously formed on both the upper and lower membranes. Infrared detector.

3. In Paragraph 2, The above thermistor material is, Composed of at least one of VOx (Vanadium Oxide), a-VOx (Amorphous Vanadium Oxide), and a-Si (Amorphous Silicon), Infrared detector.

4. In Paragraph 1, On at least one of the upper and lower surfaces of the third membrane A protective layer formed by being composed of at least one of SiNx (Silicon Nitride) and SiOx (Silicon Oxide), Infrared detector.

5. In Paragraph 1, In order to electrically connect the first membrane and the second membrane, a first-layer electrode located on the first layer and a second-layer electrode located on the second layer are formed, and The above-mentioned first-layer electrode and the above-mentioned second-layer electrode are configured to be continuously connected, Infrared detector.

6. In Paragraph 1, The above third membrane is, Characterized by being formed in a cantilever shape, Infrared detector.

7. In the infrared detector having a first sacrificial layer located on a first layer positioned on a lower substrate of the infrared detector and a second sacrificial layer located on a second layer positioned on the first layer, said infrared detector A third membrane having a form in which the first membrane on the first sacrificial layer and the second membrane on the second sacrificial layer are connected; A leg metal electrode formed on the lower part of the second membrane; and Anchor metal formed on the lower part of the second membrane; comprising Infrared detector.

8. In Paragraph 7, The first sacrificial layer and the second sacrificial layer are formed to be removable through a MEMS process. Infrared detector.

9. In Paragraph 7, The first sacrificial layer and the second sacrificial layer are composed of at least one of polyimide, spin-on carbon, and amorphous carbon. Infrared detector.

10. In Paragraph 7, The above first sacrifice layer and the above second sacrifice layer Formed by at least one of CVD (Chemical Vapor Deposition) and Spin Coating methods, Infrared detector.

11. In Paragraph 7, The above anchor metal is, Formed within the contact holes of the first sacrificial layer and the second sacrificial layer, The above anchor metal is composed of at least one metal among Al, Ti, TiN, Mo, and W. Infrared detector.

12. In a method for manufacturing an infrared detector, A first sacrificial layer forming step of forming a first sacrificial layer on the lower substrate of the infrared detector; A step of forming a first membrane on top of the first sacrificial layer formed above; A second sacrifice layer forming step of forming a second sacrifice layer on the first sacrifice layer; A second sacrificial layer etching step for etching the second sacrificial layer to form a second membrane; and A membrane forming step comprising connecting the second membrane formed above and the first membrane to form a third membrane; Method for manufacturing an infrared detector.

13. In Paragraph 12, The first sacrificial layer formation step; and the second sacrificial layer formation step; are, The method further comprises the step of forming the first sacrificial layer and the second sacrificial layer with at least one of polyimide, spin-on carbon, and amorphous carbon. Method for manufacturing an infrared detector.

14. In Paragraph 12, The above membrane formation step; is The method further comprises the step of including a metal electrode so that the second membrane and the first membrane can be continuously connected. Method for manufacturing an infrared detector.

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