KR101034647B1 - High sensitive infrared detector for ndir type gas sensor using wafer level packaging and its manufacturing method - Google Patents

Abstract

The present invention relates to an infrared sensing element for a gas sensor of NDIR type using wafer level packaging, and a method of manufacturing the same.

According to the present invention, an upper substrate on which a support layer is formed, an insulating layer formed on one surface of the support layer, an electrode layer formed on the insulating layer, a protective layer formed on the electrode layer, a first cavity is formed on an inner surface, and an infrared filter is formed on an inner surface or an outer surface thereof. An upper substrate bonded to an upper portion of the lower substrate, a getter formed on an inner surface of the upper substrate, a metal solder layer for bonding the lower substrate and the upper substrate,

Here, the lower substrate has at least one second cavity is formed on the upper surface and a sensing unit for detecting infrared rays on the upper space of each second cavity, and a support unit for supporting the sensing unit on both sides of the sensing unit is formed, at this time, The unit includes a reflective layer formed on the support layer in the insulating layer, and a sensing layer formed on the insulating layer in the protective layer and configured to be connected to the electrode layer,

The lower substrate and the upper substrate are characterized in that the inside is bonded in a vacuum state.

NDIR, Wafer Level Packaging (WLP), Carbon Dioxide, Infrared, Sensors, Bolomers, Cavities, Boards

Description

INFRARED DETECTOR FOR NDIR TYPE GAS SENSOR USING WAFER LEVEL PACKAGING AND ITS MANUFACTURING METHOD}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an infrared sensor for gas detection of a non-dispersive infrared (hereinafter referred to as NDIR) method, and more particularly, to a wafer level packaging (WLP) type bolometer. An infrared sensing element for a gas sensor of the NDIR method using a MEMS structure and a manufacturing method thereof.

Increasing the concentration of carbon dioxide (CO ₂ ) in the air is a global problem that increases the temperature of the atmosphere due to the greenhouse effect, as well as the damage to life caused by oxygen deficiency. Therefore, it is urgent to prepare the measures for the protection and improvement of the atmosphere and working environment by continuously measuring the concentration of CO2 and taking measures to control and cope with the sources. Accordingly, it is very necessary to develop a device capable of measuring the concentration of carbon dioxide.

Among the sensors for measuring the concentration of carbon dioxide in the prior art, a sensor that is currently in the spotlight is an NDIR type sensor. These NDIR sensors take advantage of the property that carbon dioxide absorbs infrared radiation at specific wavelengths. That is, the concentration of carbon dioxide is measured by measuring the change in the amount of infrared rays detected by the infrared sensing element according to the change in the amount of carbon dioxide.

1 is a schematic diagram of a sensor for detecting carbon dioxide gas of a conventional NDIR method.

Referring to FIG. 1, the conventional NDIR type carbon dioxide detection sensor includes an infrared light emitting unit 1 emitting infrared light, and openings 3a and 3b for guiding generated infrared rays and inflow and outflow of carbon dioxide, respectively. It consists of a housing 3 and an infrared sensing element 5 that absorbs infrared rays, and an infrared filter 7 for filtering infrared wavelengths is formed in front of the infrared sensing element 5. The infrared sensing element 5 varies in the amount of infrared light absorbed according to the amount of carbon dioxide, and the amount of carbon dioxide is measured using this principle. In this case, in order to accurately measure the concentration of carbon dioxide, the performance of the infrared sensing element 5 absorbing infrared rays is very important.

Conventionally, a heat absorption type sensing element such as a pyroelectric, a thermopile, a bolometer, or the like is used as an infrared sensing element used for a NDIR type gas detection sensor. Among these infrared detectors, the most powerful, easy to manufacture, and small in volume are the bolometers. Other infrared sensing devices exhibit low infrared sensitivity of about 10 ⁷ to 10 ⁸ , while infrared sensing of bolometer type infrared sensing devices is about 10 ⁸ to 10 ⁹ .

However, in this bolometer-type infrared sensing element, an essential element is the degree of vacuum inside the package in which the infrared sensing unit is located. Thermal energy (infrared rays) incident on the package of the infrared sensing device is transmitted in the package of the infrared sensing device in various forms such as radiation, conduction, and convection. Many of these types of heat transfer appear as heat loss to infrared sensing devices. This heat loss causes the degradation of the infrared sensing device located inside the package. Therefore, the method of improving the performance of the infrared sensing element located inside the package by minimizing heat loss inside the package is to keep the inside of the package in a vacuum state.

2 is a schematic view showing a vacuum packaging process of a conventional bolometer-type infrared sensing device.

Referring to FIG. 2, in the infrared sensing device using a conventional bolometer, the device wafer 11 in which the sensing unit is integrated is diced for each chip 12. Each diced chip 12 includes a substrate 11, an infrared detector 12a and a signal electrode (not shown) formed on the substrate 11. The chip 12 is mounted on the support portion 14 on which the support legs 13 are formed, and then wire bonded (15). Subsequently, the vacuum packaging of the infrared sensing element is performed by welding the cap 17 having the infrared filter 18 formed on the upper surface of the vacuum chamber 16 inside the vacuum chamber 16 to the support 14. As such, the inside of the package of the infrared sensing device is vacuumed to minimize the heat loss inside the package, thereby preventing the performance of the infrared sensing device. As a result, when infrared rays are incident from the outside through the infrared filter 18, the bolometer-type infrared detector formed on the chip 12 absorbs them, and detects the amount of infrared rays through a resistance change according to the infrared absorption.

However, such a conventional infrared sensing element has a problem that the generation of gas due to heat is inevitable when the cap 17 is bonded in the vacuum chamber 16, thereby increasing the degree of vacuum inside the package. Although a vacuum pump may be used to remove the gas generated as described above, such a vacuum pump has a problem in that manufacturing cost increases because it is expensive. In addition, in order to manufacture a cap-shaped package capable of a vacuum atmosphere inside the package, there is a need to manufacture a separate mold without using a commercially available mold.

Furthermore, in the case of such a cap package, the size of the support 14 and the cap 17 is limited to miniaturization of the infrared sensing element. Even if the infrared sensing element is implemented in a small size, the handling of each element is difficult when implementing the cap package. There is a problem that is difficult. In addition, the bolometa type infrared sensing element in the form of a cap package requires an additional device for cap packaging, increases manufacturing costs, and does not allow batch manufacturing.

Therefore, in the technical field, it is possible to easily manufacture the NDIR-type infrared sensor for gas sensors at low cost, and in particular, development of a technology for manufacturing the entire size in a very small size is required.

The present invention has been proposed to solve the above-mentioned problems, and NDIR using wafer level packaging capable of realizing a miniaturized infrared sensing device by manufacturing a chip package of the infrared sensing device using wafer level packaging (WLP). An object of the present invention is to provide an infrared sensing element for a gas sensor and a method of manufacturing the same.

In addition, another object of the present invention is to provide an infrared sensing device for NDIR gas sensor and a method of manufacturing the same using a wafer level packaging having high sensitivity by implementing the inside of the chip package of the infrared sensing device with high reliability.

In addition, the present invention provides an infrared sensing device for NDIR gas sensor using a wafer-level packaging with high yield and low manufacturing cost because there is no cracking of the device during the chip packaging process of the infrared sensing device, and a manufacturing method thereof There is another purpose.

The present invention for achieving the above object,

A lower substrate having a support layer formed on at least one surface thereof;

An insulating layer formed on one surface of the support layer;

An electrode layer formed on the insulating layer;

A protective layer formed on the electrode layer;

An upper substrate having a first cavity formed on one surface and an infrared filter formed on at least one surface thereof, the upper substrate being bonded at a wafer level to an upper portion of the lower substrate;

A getter formed on an inner surface of the upper substrate; And

A metal solder layer for bonding the upper substrate and the lower substrate; Including,

The lower substrate has at least one second cavity formed on an upper surface thereof, a sensing unit sensing infrared rays in an upper space of each of the second cavities, and a supporting unit supporting the sensing units on both sides of the sensing unit.

The sensing unit includes a reflective layer formed on the support layer in the insulating layer, and a sensing layer formed on the insulating layer in the protective layer and configured to be connected to the electrode layer.

The inside of the bonded upper substrate and the lower substrate relates to an NDIR-type gas sensor infrared sensing device using wafer level packaging, characterized in that the vacuum state.

In addition, the present invention for achieving the above object,

Providing a device wafer and a cap wafer, respectively;

Bonding the device wafer and the cap wafer to each other in a vacuum atmosphere to form a package; And

Dicing the package by individual chips; Including,

The process of preparing the device wafer,

Forming a support layer on at least one surface of the lower substrate;

Forming a reflective layer on at least one location above the support layer;

Forming an insulating layer on the support layer to include the reflective layer;

Forming a sensing layer on the insulating layer at the position where the reflective layer is formed;

Forming an electrode layer on the insulating layer in a predetermined pattern and then performing heat treatment;

Forming a protective layer on the insulating layer on which the sensing layer and the electrode layer are formed, and then removing a portion other than the portion where the sensing layer and the electrode layer are formed to open a portion of the lower substrate;

Forming a metal solder layer at a predetermined position of the lower substrate; And

Forming a first cavity on an upper portion of the lower substrate by etching the lower substrate below the sensing layer so that the sensing layer is positioned in a space; Including,

The process of preparing the cap wafer,

Providing an upper substrate and etching one surface thereof to form a second cavity;

Forming an infrared filter on an inner surface or an outer surface of the upper substrate;

Forming a getter on an inner surface of the upper substrate; And

Forming a metal solder layer at a predetermined position of the lower substrate; It relates to a method for manufacturing an infrared sensing element for a gas sensor of the NDIR method using a wafer level packaging comprising a.

According to the infrared sensing device for NDIR gas sensor using the wafer level packaging and the method of manufacturing the same according to the present invention has the following effects.

First, by using the wafer level packaging (WLP), it is possible to form a reliable vacuum atmosphere inside the packaging of the infrared sensing element.

Second, since the general semiconductor processing equipment is used, no additional equipment modification or device fabrication is required.

Third, the fabrication of a packaged infrared sensing element is simple by using bonding of wafers.

Fourth, since a separate mold is not required, it is possible to manufacture a micro infrared sensor.

Fifth, the batch production of the infrared sensing element is possible, so that the manufacturing time of the packaged infrared sensing element can be shortened and the manufacturing cost can be lowered.

Sixth, since chip-level handling is not required separately, there is no cracking of the device, thereby increasing the manufacturing yield of the infrared sensing device.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 is a schematic perspective view of an infrared sensing element for a NDIR gas sensor using wafer level packaging according to an embodiment of the present invention.

As shown in FIG. 3, the NDIR-type infrared sensor 100 for a gas sensor according to an exemplary embodiment of the present invention includes an element wafer 110 and a cap wafer 120. The device wafer 110 and the cap wafer 120 are bonded to each other in a vacuum atmosphere at the wafer level to form a package of one infrared sensing device 100. The device wafer 110 includes at least one sensing unit 113 and a support unit 115 on the lower substrate 111, and the support unit 115 receives the infrared sensing signal detected by the sensing unit 113. It is configured to serve to deliver to the electrode 117 located in the upper side end portion (110). The sensing units 113 may be arranged in M × N to constitute one infrared sensing element 110. In addition, the upper cap wafer 120 includes an upper substrate 121 having an infrared filter 123 formed on both surfaces thereof. In the drawing, the electrode 117 is open to the outside so as to be connected to an external electrode through wire bonding as an example, but in another example, the electrode 117 may be connected to a lower portion thereof through a through hole formed in the lower substrate 111. have.

4 is a cross-sectional view of the infrared sensor for a gas sensor of the NDIR method according to the present invention.

As shown in FIG. 4, the infrared sensing device 200 according to the present invention is largely composed of an element wafer 210 and a cap wafer 220. As shown in the figure, the lower element wafer 210 and the upper cap wafer 220 are bonded and packaged at the wafer level to implement the infrared sensing device 200. At this time, the wafer level packaging of the infrared sensing element is performed in a vacuum atmosphere. Therefore, the inside of the infrared sensing device package is in a vacuum state.

The device wafer 210 according to the present invention includes a lower substrate 211 having a support layer 212 formed on at least one surface thereof, an insulating layer 213 formed on the support layer 212 formed on one surface thereof, and an electrode layer formed on the insulating layer 213. 214 and a protective layer 215 formed on the electrode layer 214. The lower substrate 211 may use a silicon substrate, but the present invention is not limited thereto. In addition, the support layer 212 is for the thermal isolation structure shape, it is preferable that the silicon nitride film of a low stress of approximately 4000 kPa thickness.

In addition, the lower substrate 211 is formed with at least one first cavity (cavity) 218 on the upper surface, the sensing unit (A) for detecting infrared rays in the upper space of the first cavity (218), and such a detection Support portions B supporting the sensing portion A are formed on both sides of the portion A, respectively. The sensing unit A serves to detect an amount of infrared rays that changes according to the amount of gas such as carbon dioxide, for example, and the supporting unit B transfers the signal sensed by the sensing unit A to an external signal electrode (not shown). At the same time it serves to support the sensing unit (A) in the upper space of the first cavity (218).

The sensing unit A constituting the infrared sensing element 200 of the present invention is formed on the reflective layer 216 formed on the support layer 212 in the insulating layer 213 and on the insulating layer 213 in the protective layer 215. And a sensing layer 217 configured to be connected to the electrode layer 214. The electrode layer 214 is connected to the sensing layer 217 of the sensing unit A in the form of a metal thin film, and transmits a signal regarding infrared absorption detected by the sensing layer 217 to an external signal electrode (not shown). Play a role. In addition, the sensing layer 217 functions to detect infrared rays, and for this purpose, it is preferable to use a material such as VOx, a-Si, V-W-O, or the like as the sensing material of the sensing layer 217. In addition, the reflective layer 216 is formed on the support layer 212 to achieve a resonance effect by infrared reflection, and may be formed of a metal thin film. For example, it is preferably formed of one selected from aluminum, chromium, and gold deposited to a thickness of approximately 1000 microns. The insulating layer 213 is formed for the insulation between the reflective layer 216 and the sensing layer 217 and the infrared resonance operation. The insulating layer 213 is preferably formed of a silicon nitride film having a thickness of about 2000 kHz.

On the other hand, the protective layer 215 is to protect the lower element wafer 210 as a whole, it is preferably formed of a silicon nitride film having a thickness of approximately 4000 kPa. In addition, a metal solder layer 224 for wafer bonding is formed on the protective layer 215. The metal solder layer 224 is preferably in the range of 0.1 ~ 4㎛. Optionally, through electrodes 219 are formed at both ends of the lower substrate 211. In another example, as illustrated in FIG. 3, the electrode layer 214 may be opened to the outside. In this case, it may be connected to the external electrode through wire bonding.

In addition, the cap wafer 220 according to the present invention is the upper substrate 221 bonded to the lower substrate 211 described above, the infrared filter 222 formed on the inner and outer surfaces of the upper substrate 221, the infrared filter on the inner surface A getter 223 formed on the 222 and a metal solder layer 224 for bonding the two substrates 211 and 221 are included. That is, by bonding the upper and lower substrates 211 and 221 using the metal solder layer 224, the infrared sensing device 200 is completed in the form of a package at the wafer level. The upper substrate 221 has a second cavity 225 formed therein to be bonded to the lower substrate 211. The second cavity 225 may be formed to include other components such as the protective layer 215 as well as the plurality of sensing units A and the support B formed on the lower substrate 211.

In this case, infrared filters 222 are formed on the inner surface or the outer surface of the upper substrate 221 on which the second cavity 225 is formed. The infrared filter 222 filters and transmits light having an infrared wavelength of 4.25 to 4.35 µm. More preferably, light of 4.26 mu m infrared wavelength is transmitted. At least one getter 223 is formed on an inner surface of the second cavity 225. The getter 223 functions to increase the degree of vacuum inside the package by absorbing the gas generated in the process of packaging the lower substrate 211 and the upper substrate 221 at the wafer level.

At this time, the lower substrate 211 and the upper substrate 221 are bonded using various metal bonding (metallic bonding) in a vacuum atmosphere of approximately 10 ^-4 torr. As the metal bonding method, thermocompression bonding, eutectic bonding, or the like may be used. As such, by bonding the two substrates 211 and 221 in a vacuum atmosphere, the sensing unit A may be positioned inside the package in a vacuum state, and when the plurality of sensing units A are configured, the sensing unit A is protected by the upper substrate 221. The individual sensing units A may proceed without breaking the device in a subsequent dicing process.

As described above, the infrared sensing device 200 of the present invention may be implemented as a package at the wafer level, the device wafer 210 and the cap wafer 220, the inside of the package is in a vacuum state. Furthermore, the device wafer 210 includes a sensing unit A and a support unit B supporting the sensing unit A in the upper space of the first cavity in a lower substrate having a first cavity formed thereon. And further comprises an infrared filter and a getter on the upper substrate. Preferably the support (B) is implemented in a zigzag shape.

5 is a schematic view showing a wafer level packaging process of the infrared sensing device.

As shown in FIG. 5, in order to wafer-level package the infrared sensing device 200 according to the present invention, the device wafer 210 and the cap wafer 220 are mounted by mounting necessary devices through separate processes at the wafer level, respectively. To produce. Subsequently, two wafers 210 and 220 are bonded to each other through wafer bonding to be packaged. At this time, the bonding process of the two wafers 210 and 220 is performed in a vacuum atmosphere. For example, it is preferable to join in a vacuum chamber. As a result, a vacuum is maintained in the two bonded wafers 210 and 220. The infrared sensing device 200 is completed by dicing the two bonded wafers 210 and 220 at the wafer level.

As described above, in the present invention, the infrared sensing element 200 can be completed by fabricating, bonding, and dicing a wafer at a wafer level through a predetermined semiconductor process.

Hereinafter, a method of manufacturing an infrared sensing element for an NDIR type gas sensor using wafer level packaging according to the present invention will be described with reference to FIGS. 6 to 9.

6 is a schematic diagram illustrating a method of manufacturing an element wafer of an NDIR-type gas sensor infrared sensor using wafer level packaging according to an embodiment of the present invention.

As shown in FIG. 6 (a), in order to manufacture the device wafer 310 of the infrared sensing device 300 according to the present invention, first, a support layer 312 for thermal isolation structure is formed on at least one of an upper surface and a lower surface. The formed lower substrate 311 is provided. The lower substrate 311 may be a silicon substrate, but the present invention is not limited thereto. The support layer 312 is provided for the thermal isolation structure on the upper and lower portions of the lower substrate 311. For example, a low pressure chemical vapor deposition (LPCVD) method, a plasma enhanced chemical vapor deposition (PECVD) It can be implemented by forming a silicon nitride film of low stress using a Vapor Deposition method.

Next, in the present invention, as shown in FIG. 6 (b), the reflective layer 313 is patterned at a predetermined position on the support layer 312 through a conventional photolithography process. The reflective layer 313 is formed on the support layer 312 for the resonance effect by infrared reflection. The reflective layer 313 may be formed by depositing and patterning a metal thin film using a conventional photolithography process.

Subsequently, in the present invention, as shown in FIG. 6C, the insulating layer 314 is formed to include the reflective layer 313 on the lower substrate 311 on which the reflective layer 313 is formed. The insulating layer 314 is preferably deposited by LPCVD, PECVD, etc. in consideration of the process temperature at which the infrared sensing element for the carbon dioxide gas sensor is manufactured, and is preferably formed by depositing a silicon nitrite (SiNx) material. The insulating layer 314 is formed for the insulating and infrared resonant action between the reflective layer 313 and the sensing layer 315 described later.

Subsequently, in the present invention, as illustrated in FIG. 6D, the sensing layer 315 is deposited and patterned at a predetermined position on the insulating layer 314, preferably at a position where the reflective layer 313 is formed on the insulating layer 314. do. The sensing layer 315 is VO _x . It is preferable to use materials such as a-Si and VWO. The sensing layer 315 is formed by coating a photosensitive film on the insulating layer 314 and then exposing and developing a predetermined pattern to form a predetermined pattern, and then depositing the above-described sensing material and then removing the photosensitive film. It can be prepared through a photolithography process.

Next, in the present invention, as shown in FIG. 6E, the electrode layer 316 is formed on the insulating layer 314. The electrode layer 316 is formed on the insulating layer 314 in the form of a metal thin film. In this case, in the case of the electrode layer 316 connected to the sensing layer 315, the support portion B having a zigzag shape on both sides of the sensing layer 315 may be stably supported so as to stably support the sensing layer 315 suspended in the air. Is formed according to. The electrode layer 316 is formed by forming a photosensitive film pattern on a portion where the electrode layer 316 is not formed, such as the sensing layer 315, and then depositing a metal thin film and then removing the photosensitive film (eg, zigzag). Only the electrode layer 316 can be formed, and the present invention is not limited to the type, composition, deposition method, and the like of the metal. In this case, when the plurality of sensing layers 315 are connected by M × N, the electrode layers 316 are connected to each other with the electrode layers 316 in the neighboring support part B, and the electrode layers 316 at the end thereof are connected to the lower substrate. It is connected to the external signal electrodes formed at both ends of 311). As a result, the electrode layer 316 functions to connect the sensing layer 315 and the external signal electrode of the corresponding sensing unit A through the respective supporting units B, respectively.

If the infrared sensing element 300 according to the present invention includes one sensing layer 315, the electrode layer 316 is connected to external signal electrodes formed at both ends of the signal detected by the sensing layer 315. . In this case, the electrode layers 316 at both ends may be used as external signal electrodes.

Subsequently, in the present invention, the lower substrate 311 on which the electrode layer 316 is formed is heat treated, and the upper portion of the sensing layer 315 is oxidized through such heat treatment. By the oxidation treatment, the material constituting the sensing layer 315 may be amorphous to exhibit excellent infrared sensing performance. The present invention is not limited to the heat treatment temperature, it is preferable to heat treatment, for example about 280 ~ 320 ℃.

Subsequently, as shown in FIG. 6F, the protective layer 317 is formed on the lower substrate 311 on which the sensing layer 315 and the electrode layer 316 are formed. The protective layer 317 is formed to include the insulating layer 314, the sensing layer 315, and the electrode layer 316, which is a layer for protecting the entire infrared sensing device thus manufactured in a subsequent silicon bulk etching process. . The protective layer 317 is preferably formed by depositing and patterning a silicon nitride film using LPCVD and PECVD methods. Although not shown in the drawing, when the signal electrode layer is formed at the end of the lower substrate 311, the protective layer on the signal electrode layer may be opened first.

Next, in the present invention, as shown in FIG. 6 (g), the lower substrate 311 manufactured through the above process is opened to a portion where the electrode layer 316 pattern is not formed using dry etching equipment ( H) This opening may be performed by forming a photosensitive film pattern only on a portion where the electrode layer 316 is formed, and then etching and opening the supporting layer 312, the insulating layer 314, and the protective layer 317 through a dry etching process. And removing the photosensitive film. The photosensitive film pattern is preferably formed in a zigzag pattern to determine the shape of the support B. FIG.

By forming the protective layer 317 as described above, it can be seen that the support part B supporting the sensing part A and the sensing part A on both sides is formed, and the support part B supports the zigzag pattern. It may be formed as a bridge to be connected to the external signal electrode or the electrode layer 310 of the neighboring support (B).

Next, in the present invention, as shown in FIG. 6 (h), the metal solder layer 318 for bonding the lower substrate 311 with the upper substrate described later is formed and patterned. The metal solder layer 318 may use any one of Au, AuSn, Sn, Cu, Ag, or a mixture thereof as the bonding metal. In an embodiment of the present invention, Au 80 wt% + Sn 20 wt% may be used. However, the present invention is not limited thereto.

Subsequently, in the present invention, as shown in FIG. 6 (i), the portion corresponding to the sensing unit A and the support unit B on the lower substrate 311 of the device wafer 310 manufactured as described above may be wet-etched. The thermal isolation structure is formed by forming one cavity 319. As a bulk wet etchant, KOH is preferred, but is not limited thereto. The sensing unit A is positioned on the upper space of the first cavity 319 so that the sensing unit A has a thermal isolation structure. This makes it possible to implement a more sensitive infrared sensing element.

FIG. 7 is a schematic view illustrating a method of manufacturing a cap wafer of an NDIR-type infrared sensor for gas sensor using wafer level packaging according to an exemplary embodiment of the present invention.

As shown in FIG. 7A, in order to manufacture the cap wafer 320 of the infrared sensing device 300 according to the present invention, a double-side polished upper substrate 321 is first provided. It is preferable to use a silicon substrate as the upper substrate 321, but the present invention is not limited thereto. One surface of the upper substrate 321 is bulk etched to form a second cavity 322. The second cavity 322 is preferably formed to include various components formed on the device wafer 310 described above.

Subsequently, as shown in FIG. 7B, an infrared filter 323 for filtering and transmitting specific infrared rays is formed on at least one surface of the upper substrate 321 on which the second cavity 322 is formed. The infrared filter 323 preferably uses a material such as Ge or ZnS.

Next, in the present invention, as shown in FIG. 7C, a getter 324 is formed and patterned on the infrared filter 323 formed in the second cavity 322 of the upper substrate 321. The getter 324 is formed to adsorb the gas generated when the upper and lower substrates 311 and 321 are bonded to each other in order to form the infrared sensing device as a package. It is preferable to form.

Subsequently, in the present invention, as shown in FIG. 7D, the metal solder layer 325 for bonding to the lower substrate 311 is formed and patterned. The metal solder layer 325 is formed in a pattern for bonding the lower substrate 311 and the upper substrate 321 manufactured in the process of FIG. 6 at the wafer level to package the infrared substrate. The metal solder layer 321 preferably uses a material such as Au, AuSn, Sn, Cu, Ag, or the like as the bonding metal.

As described above, the second cavity 322 is formed on one surface of the upper substrate 321, and then the infrared filter 323 is formed on both surfaces thereof, and on the infrared filter 323 formed in the second cavity 322. The cap wafer 320 is fabricated at the wafer level in accordance with the present invention by forming one or more getters 324 and metal solder layers 325.

FIG. 8 is a schematic diagram illustrating a bonding process between an element wafer and a cap wafer of an NDIR type infrared sensor for a gas sensor at a wafer level according to an exemplary embodiment of the present invention.

Referring to FIG. 8, the infrared sensing device according to the present invention bonds the device wafer 310 and the cap wafer 320 manufactured as shown in FIGS. 6 and 7 by using various metal bonding methods in the vacuum chamber 81. . As the metal bonding method, thermocompression bonding, eutectic bonding, or the like can be used. At this time, it is preferable to proceed with the bonding process by considering the process temperature etc. which the infrared sensing element for carbon dioxide gas sensors are manufactured suitably.

In the drawing, as an embodiment of the present invention, the device wafer 310 is placed on the hot plate 82 and the cap wafer 320 is disposed on the upper portion of the cap wafer 320. By pressing at a constant pressure from the device wafer 310 and the cap wafer 320 are bonded and packaged. Here, the packaged two wafers 310 and 320 are joined by metal solder layers 318 and 321.

Infrared sensor for object detection is manufactured by dicing the bonded package for each chip.

9 is a schematic diagram illustrating a signal electrode forming method of an NDIR-type gas sensor infrared sensor using wafer level packaging according to an exemplary embodiment of the present invention.

As shown in FIG. 9, there are two methods for forming a signal electrode of the infrared sensing element according to the present invention. As shown in FIG. 9A, after the wafer bonding process between the device wafer 310 and the cap wafer 320, a via hole is formed from the rear surface of the lower device wafer 310 to the signal electrode. 91). The through hole 91 may be formed by patterning using a photoresist and then using deep reactive ion etching (DRIE). The through electrode 92 is formed in the through hole 91 by using a plating method such as electroplating or electroless plating. The through electrode 92 may be formed by plating a metal material on the inner surface of the through hole 91 or by filling the through hole 91 with a metal material. The through electrode 92 is preferably connected to the electrode layer 316 on the upper side and the solder bump 93 is formed on the lower side. The through electrode 92 may be formed of a material such as Au, Cu, Ni, NiCr, but the present invention is not limited thereto.

In the second method, as shown in FIG. 9B, after the wafer bonding process of the device wafer 310 and the cap wafer 320, the lower device wafer 310 is diced and the electrode layer 316 formed at the end portion thereof. Only the protective layer 317 formed on the upper portion is removed, and the electrode layer 316 is opened. Then, the electrode layer 316 is connected to the outside through a wire bonding 94.

The infrared sensing device of the present invention manufactured by the above-described manufacturing process is easy to manufacture, batch production, high reproducibility, and mass production by using the MEMS process. In addition, since it is possible to produce a large amount of infrared sensing element in high yield, there is an effect that the manufacturing cost is low.

As described above, the present invention has been described based on the embodiments, but the present invention is not limited thereto. Various modifications and variations are possible to those skilled in the art within the technical scope of the appended claims, and it should be understood that all such modifications are within the scope of the present invention if they are within the technical scope of the claims.

The generation of carbon dioxide in the air and in the working environment not only damages life, but also the greenhouse effect caused by carbon dioxide has emerged as a problem for mankind on earth. Therefore, it is very important to accurately measure the concentration of carbon dioxide and take countermeasures accordingly.

Currently, a sensor that can measure the concentration of carbon dioxide has been developed, and one of the most popular sensors is NDIR type gas sensor. Infrared sensing element is used for the NDIR type gas sensor. In other words, the concentration of carbon dioxide is measured by measuring the amount of infrared light that changes according to the amount of carbon dioxide in the infrared sensing element. At this time, in order to accurately measure the concentration of carbon dioxide, such an infrared sensing element should be a high performance.

In view of this aspect, the infrared sensing element according to the present invention provides high performance by minimizing heat loss of the infrared sensing unit by supporting the infrared sensing unit in the air and connecting the substrate to the substrate using a support unit to form a thermal isolation structure under the infrared sensing unit. To make it work. In addition, since the infrared sensing device of the present invention is processed at the wafer level and can be miniaturized and can be easily produced in large quantities at low cost, it may be very usefully applied in the technical field for detecting carbon dioxide in the future.

1 is a schematic diagram of a sensor for detecting carbon dioxide gas of a conventional NDIR method.

2 is a schematic view showing a vacuum packaging process of a conventional bolometer-type infrared sensing device.

3 is a schematic perspective view of an infrared sensing element for a NDIR gas sensor using wafer level packaging according to an embodiment of the present invention.

4 is a cross-sectional view of the infrared sensor for a gas sensor of the NDIR method according to the present invention.

5 is a schematic view showing a wafer level packaging process of the infrared sensing device.

6 is a schematic diagram illustrating a method of manufacturing an element wafer of an NDIR-type gas sensor infrared sensor using wafer level packaging according to an embodiment of the present invention.

FIG. 7 is a schematic view illustrating a method of manufacturing a cap wafer of an NDIR-type infrared sensor for gas sensor using wafer level packaging according to an exemplary embodiment of the present invention.

FIG. 8 is a schematic diagram illustrating a bonding process between an element wafer and a cap wafer of an NDIR type infrared sensor for a gas sensor at a wafer level according to an exemplary embodiment of the present invention.

9 is a schematic diagram illustrating a method of forming a signal electrode of an NDIR-type gas sensor infrared sensor using wafer level packaging according to an exemplary embodiment of the present invention.

 Explanation of symbols on the main parts of the drawings

110,210,310: device wafer 120,220,320: cap wafer

211,311: Lower board 221,321: Upper board

312: support layer 313: reflective layer

314: insulating layer 315: sensing layer

316: electrode layer 317: protective layer

Claims (30)

A lower substrate having a support layer formed on at least one surface thereof; An insulating layer formed on one surface of the support layer; An electrode layer formed on the insulating layer; A protective layer formed on the electrode layer; An upper substrate having a first cavity formed on one surface and an infrared filter formed on at least one surface thereof, the upper substrate being bonded at a wafer level to an upper portion of the lower substrate; A getter formed on an inner surface of the upper substrate; And A metal solder layer for bonding the upper substrate and the lower substrate; Including, The lower substrate has at least one second cavity formed on an upper surface thereof, a sensing unit sensing infrared rays in an upper space of each of the second cavities, and a supporting unit supporting the sensing units on both sides of the sensing unit. The sensing unit includes a reflective layer formed on the support layer in the insulating layer, and a sensing layer formed on the insulating layer in the protective layer and configured to be connected to the electrode layer. The inside of the bonded upper substrate and the lower substrate is an infrared sensing element for a gas sensor of the NDIR method using wafer level packaging, characterized in that the vacuum state. The method of claim 1, The lower substrate includes at least one through hole having a through electrode formed therein, and the through electrode is connected to an electrode layer at an upper portion thereof and a solder bump is formed at a lower portion thereof. Infrared Sensing Device The method of claim 2, The through electrode is an infrared sensing element for a gas sensor of the NDIR method using wafer-level packaging, characterized in that formed by depositing any one selected from Au, Cu, Ni, NiCr. The method of claim 1, The lower substrate is a protective layer formed on the electrode layer is removed, the electrode layer is open, the open electrode layer is infrared for the NDIR gas sensor using a wafer level packaging, characterized in that connected to the external signal electrode by wire bonding. Sensing element. The method of claim 1, Wafer-level packaging, characterized in that signal electrodes are formed on both ends of the lower substrate, the electrode layers of the support part are connected to the electrode layers of the support parts adjacent to each other, and the electrode layers of the outermost support part are connected to the signal electrodes. Infrared sensing element for gas sensor of NDIR type. The method of claim 1, The support unit is an infrared sensing element for a gas sensor of the NDIR method using wafer level packaging, characterized in that the zigzag shape. The method of claim 1, Infrared sensing device for a gas sensor of the NDIR method using wafer-level packaging, characterized in that the support layer, insulating layer, protective layer each made of a silicon nitride film. The method of claim 1, The reflective layer is an infrared sensing element for a gas sensor of the NDIR method using wafer level packaging, characterized in that made of one selected from aluminum, chromium and gold. The method of claim 1, The sensing layer is an infrared sensing element for a gas sensor of the NDIR method using wafer level packaging, characterized in that made of an infrared sensing film of a material selected from VOx, a-Si, V-W-O. The method of claim 1, The insulating layer is an infrared sensing element for a gas sensor of the NDIR method using a wafer level packaging, characterized in that the deposited by SiNx material. The method of claim 1, The infrared filter is an infrared sensing element for a gas sensor of the NDIR method using wafer level packaging, characterized in that formed in a thin film form of any one selected from Ge, ZnS. The method of claim 11, The infrared filter is an infrared sensing element for a gas sensor of the NDIR method using wafer level packaging, characterized in that to transmit light of 4.20 ~ 4.30㎛ wavelength. The method of claim 1, The getter is an infrared sensing element for a gas sensor of the NDIR method using wafer level packaging, characterized in that the thin film is made of a Ti material. The method of claim 1, The metal solder layer is an infrared sensing element for NDIR gas sensor using wafer level packaging, characterized in that it comprises at least one material selected from Au, Sn, AuSn, Cu, Si. The method of claim 14, The metal solder layer is an infrared sensing element for a gas sensor of the NDIR method using wafer level packaging, characterized in that containing Au 80wt% + Sn 20wt%. The method of claim 14, The metal solder layer is an infrared sensing element for a gas sensor of the NDIR method using wafer level packaging, characterized in that the thickness has a range of 0.1 ~ 4㎛. Providing a device wafer and a cap wafer, respectively; Bonding the device wafer and the cap wafer to each other in a vacuum atmosphere to form a package; And Dicing the package by individual chips; Including, The process of preparing the device wafer, Forming a support layer on at least one surface of the lower substrate; Forming a reflective layer on at least one location above the support layer; Forming an insulating layer on the support layer to include the reflective layer; Forming a sensing layer on the insulating layer at the position where the reflective layer is formed; Forming an electrode layer on the insulating layer in a predetermined pattern and then performing heat treatment; Forming a protective layer on the insulating layer on which the sensing layer and the electrode layer are formed, and then removing a portion other than the portion where the sensing layer and the electrode layer are formed to open a portion of the lower substrate; Forming a metal solder layer at a predetermined position of the lower substrate; And Forming a first cavity on an upper portion of the lower substrate by etching the lower substrate below the sensing layer so that the sensing layer is positioned in a space; Including, The process of preparing the cap wafer, Providing an upper substrate and etching one surface thereof to form a second cavity; Forming an infrared filter on at least one surface of the upper substrate; Forming a getter on an inner surface of the upper substrate; And Forming a metal solder layer at a predetermined position of the lower substrate; Method for manufacturing an infrared sensing element for a gas sensor of the NDIR method using wafer level packaging comprising a. The method of claim 17, The step of forming a package by bonding the device wafer and the cap wafer, Providing the device wafer and the cap wafer in a vacuum chamber; And Arranging the metal solder layers of the two wafers to be bonded to each other, and then bonding the two wafers using a conventional metal alloying method; Method of manufacturing an infrared sensing element for a gas sensor of the NDIR method using a wafer level packaging comprising a. The method of claim 18, The metal bonding method is a method of manufacturing an infrared sensing element for a gas sensor of the NDIR method using wafer-level packaging, characterized in that using one method selected from thermocompression bonding, eutectic bonding. The method of claim 17, The etching of the upper and lower substrates is a method of manufacturing an infrared sensor for NDIR gas sensor using wafer level packaging, characterized in that using a KOH solution. The method of claim 17, The support layer, the insulating layer, and the protective layer, each of the manufacturing method of the infrared sensor for NDIR gas sensor using wafer level packaging, characterized in that the deposition is formed by one of the selected method of LPCVD or PECVD. The method of claim 17, Forming the sensing layer, Applying a photosensitive film on the insulating layer; Depositing a sensing material on an insulating layer at a position where the reflective layer is formed; And Removing the photosensitive film by a conventional photolithography process; A method of manufacturing an infrared sensing element for a gas sensor of the NDIR method using a wafer level packaging comprising a. The method of claim 17, The sensing layer and the electrode layer is connected to each other, the electrode layer connected to the sensing layer is a manufacturing method of the infrared sensor for NDIR gas sensor using a wafer level packaging, characterized in that formed in a zigzag shape on both sides of the sensing layer. The method of claim 17, The method may further include forming a signal electrode at both ends of the upper portion of the lower substrate. The electrode layer is connected to the electrode layer adjacent to each other, the outermost electrode layer is a method of manufacturing an infrared sensor for NDIR gas sensor using a wafer level packaging, characterized in that connected to the signal electrode. The method of claim 17, The heat treatment is a method of manufacturing an infrared sensing element for a gas sensor of the NDIR method using a wafer level packaging, characterized in that made in the range of 280 ~ 320 ℃. The method of claim 17, The getter is a method of manufacturing an infrared sensing element for a gas sensor of the NDIR method using wafer-level packaging, characterized in that the deposition by one method selected from sputtering deposition method and ion beam deposition method. The method of claim 26, The getter is a method for manufacturing an infrared sensing element for a gas sensor of the NDIR method using wafer level packaging, characterized in that formed by depositing a Ti metal material in a thin film form. The method of claim 17, After the process of bonding the device wafer and the cap wafer, Forming through holes at both ends of the lower substrate of the device wafer; Forming a through electrode on an inner surface of the through hole; And Forming a solder bump on an upper portion of the through electrode and connecting the electrode layer to a lower portion of the through electrode; Method of manufacturing an infrared sensing element for a gas sensor of the NDIR method using a wafer level packaging, characterized in that it further comprises. The method of claim 28, The through-hole is a manufacturing method of the infrared sensor for gas sensor of the NDIR method using wafer-level packaging, characterized in that using the DRIE method. The method of claim 17, After the process of bonding the device wafer and the cap wafer, Removing the protective layer formed on the electrode layer from the device wafer to open the electrode layer; And Connecting the open electrode layer to an external signal electrode by wire bonding; Method of manufacturing an infrared sensing element for a gas sensor of the NDIR method using a wafer level packaging, characterized in that it further comprises.

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