KR101068042B1 - Micro infrared sensor for human detection and its manufacturing method - Google Patents

Abstract

Disclosed is a miniaturized human infrared sensor and a method of manufacturing the same.

The ultra-small human body infrared sensor according to the present invention,

A lower substrate in which a signal processing unit is integrated through a CMOS process; At least one infrared sensing element formed on the lower substrate and electrically connected to the signal processor; An upper substrate having a cavity formed on one surface thereof and bonded at a wafer level on the lower substrate such that the infrared sensing element is included in the cavity; An infrared filter formed on at least one surface of the upper substrate; A getter formed in the cavity to absorb the gas released during the bonding; A metal solder layer for bonding the upper substrate and the lower substrate; An electrode pad formed on the lower substrate to electrically connect the signal processor with an external electrode; Including,

At this time, the inside of the bonded upper substrate and the lower substrate is characterized in that the vacuum state.

Infrared sensor, cavity, wafer level, vacuum package

Description

Miniature infrared sensor for human body detection and its manufacturing method {MICRO INFRARED SENSOR FOR HUMAN DETECTION AND ITS MANUFACTURING METHOD}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an infrared sensor for detecting a human body, and in particular, a device chip in which an infrared sensing element and a signal processing unit are formed monolithically, and a cap wafer on which an infrared filter is formed is packaged in a vacuum at a wafer level to provide a single chip. The present invention relates to an ultra-small infrared sensor for detecting a human body and a method of manufacturing the same, which are dramatically reduced in overall chip size by forming a (SoC: System on a Chip).

Infrared radiation is a type of electromagnetic wave whose wavelength is longer than visible light, and is emitted from objects in all natural systems including humans. The higher the temperature of the object, the shorter the maximum peak wavelength of the radiated energy, and the lower the temperature, the longer the maximum peak wavelength of the radiated energy. For example, the sun at high temperatures emits energy at the maximum peak wavelength in the visible region, and humans emit energy at the maximum peak wavelength in the infrared region.

An infrared sensor is a sensor that detects infrared rays emitted by an object and measures the presence or absence of an object or a distance to the object using the magnitude of thermal energy of the infrared ray. Such infrared sensors are applied to various fields. For example, the automatic door can detect the presence of a person to automatically open or close the door or automatically turn on / off the lights, and the security device to check the intrusion of outsiders in the building or the presence and location of the human body in the middle of the night to detect the wind direction and wind speed. It can be applied to air conditioners and the like to adjust the.

The Energy Star program, launched in the United States in 1992, has expanded into a variety of products, starting with the labeling of computers and monitors. The Energy Star program improves the energy efficiency of electronic products and reduces the standby power consumption to efficiently manage the overall energy consumption. Each company is working to realize Green Technology by developing energy-efficient and eco-friendly products that meet the recommendations of the Energy Star program.

One of the efforts to save energy is the application of infrared sensors for human body detection. By using infrared sensor for detecting the human body, the amount of power used is adjusted according to the presence or absence of the human body to minimize the wasted energy and increase the overall energy efficiency. The technology to efficiently manage the energy consumption by applying the infrared sensor for detecting the human body to the product is more necessary in products such as mobile phones, personal digital assistants (PDAs), and mobile phones using batteries. In particular, the sensor size must be very small in order to be applied to the miniaturized products such as mobile phones.

Conventionally, infrared sensing elements commonly used in such infrared sensors include heat absorbing sensing elements such as pyroelectric, thermopile, and bolometer. Among these infrared sensors, the bolometer is the most powerful, easy to manufacture and small in volume. When the bolometer absorbs infrared rays emitted from the human body, the infrared rays are detected by measuring the change in electrical resistance due to the temperature rise. Other sensing devices exhibit low infrared sensitivity of 10 ⁷ to 10 ⁸ cm ^1/2 W ^-1 , while infrared sensitivity of the bolometer is 10 ⁸ to 10 ⁹ cm㎐ ^1/2 W ^-1 . . Volometer materials require high TCR (Temperature Coefficient of Resistance) values, low device resistance, and connectivity to IC processes.

1 is a schematic view showing a manufacturing process of a conventional bolometer-type infrared sensor.

As shown in FIG. 1, an infrared sensor 10 using a conventional bolometer dicing an element wafer 11 in which an infrared sensing element is integrated for each chip 12. Each diced chip 12 includes a substrate 12a, an infrared detector 12b and a signal electrode 12c formed on the substrate 12a. The chip 12 is mounted on the support part 14 on which the support legs 13 are formed, and then wire bonded to connect the signal electrode 12c to the external electrode.

Subsequently, the vacuum packaging of the infrared sensor is completed by bonding the cap 17 having the infrared filter 18 formed on the upper surface to the support 14 in the vacuum chamber 16 having a vacuum inside. In this way, by vacuuming the inside of the package of the infrared sensor to minimize the heat loss inside the package to prevent degradation of the infrared detection unit. As a result, when infrared rays are incident from the outside through the infrared filter 18, the bolometer-type infrared sensing element formed on the chip 12 is absorbed and connected to an external PCB to change the resistance according to the infrared absorption. It is possible to determine the presence or absence.

However, in the conventional infrared sensor 10, the infrared sensing element is manufactured as a chip 12 on the wafer 11, separated into individual chips 12 through dicing, and then individually packaged in the vacuum chamber 16. do. At this time, the vacuum packaging process is a process required for maintaining the performance of the infrared sensor 10, but there is a problem that a large cost is required so as to occupy a substantial portion of the total cost of the MEMS device. In addition, when the cap 17 is bonded in the vacuum chamber 16, the generation of gas due to heat is inevitable, and thus there is a problem in that the degree of vacuum inside the package is increased. Although a vacuum pump is used to remove the gas generated as described above, such a vacuum pump has a problem of causing an increase in manufacturing cost because it is expensive. In addition, in order to manufacture a cap shape that can maintain a vacuum inside the vacuum package during manufacturing, there is a need to manufacture a separate mold without using a commercially available mold.

In addition, the support 14 and the cap 17 used in such a conventional infrared sensor is a significant obstacle to miniaturization of the infrared sensor due to its size. In particular, the application of the infrared sensor to small portable products such as mobile phones, personal digital assistants (PDAs), MP3 players, laptops, etc. has a problem that the use of the infrared sensor is limited and the size of the products is limited. In addition, the infrared sensor implemented as a cap-type package has a disadvantage in that a batch manufacturing of the sensor is impossible because an additional device is required for the vacuum packaging of the cap and the vacuum packaging must be performed for each individual chip.

Therefore, in the technical field, it is possible to mass-produce an infrared sensor at a low cost in a large quantity, and in particular, the development of a technology for manufacturing the size of the infrared sensor in a very small size has been required.

The present invention has been proposed to solve the above-mentioned problems, and an object of the present invention is to provide an ultra-miniature infrared sensor for detecting a human body and a method of manufacturing the same by vacuum packaging an infrared sensor through wafer level packaging (WLP).

Another object of the present invention is to provide an ultra-small infrared sensor for detecting a human body and a method of manufacturing the same.

In addition, the present invention is to provide an ultra-compact infrared sensor for detecting the human body and a method of manufacturing the same that can be produced in a high yield and a large amount of batch production without the breakage of the device in the packaging process of the infrared sensor, and lowering the manufacturing cost. have.

The present invention for achieving the above object,

A lower substrate in which a signal processing unit is integrated through a CMOS process;

At least one infrared sensing element formed on the lower substrate and electrically connected to the signal processor;

An upper substrate having a cavity formed on one surface thereof and bonded at a wafer level on the lower substrate such that the infrared sensing element is included in the cavity;

An infrared filter formed on at least one surface of the upper substrate;

A getter formed in the cavity to absorb the gas released during the bonding;

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

An electrode pad formed on the lower substrate to electrically connect the signal processor with an external electrode; Including,

The inside of the bonded upper substrate and the lower substrate relates to an ultra-small human body sensing infrared sensor, characterized in that the vacuum state.

In the present invention, each of the infrared sensing element,

A reflective layer formed on the lower substrate; A sensing layer formed on a space above the reflective layer; A support layer formed on a lower surface of the sensing layer to support the sensing layer; A protective layer formed on an upper surface of the sensing layer; And a support for supporting the sensing layer such that the sensing layer has a structure supported on the space. It is preferable to include.

At this time, the infrared sensor of the present invention is characterized in that the length of the horizontal and vertical has a range of 0.5 ~ 2.0mm respectively.

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 at a wafer level in a vacuum atmosphere to form a package; And

Dicing the package into individual chips; Including

The process of preparing the device wafer,

Integrating a predetermined signal processor on the lower substrate through a CMOS process;

Forming electrode pads electrically connected to the signal processor at both ends of the lower substrate;

Forming at least one infrared element for sensing a human body using a system on a chip (SoC) monolithically with the signal processor on the lower substrate; And

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

The process of preparing the cap wafer,

Providing an upper substrate having a cavity formed on one surface thereof;

Forming an infrared filter on at least one surface of the upper substrate;

Forming a getter on an inner surface of the upper substrate on which the cavity is formed; And

Forming a metal solder layer at a predetermined position of the upper substrate; It relates to a method of manufacturing an ultra-small human body detection infrared sensor comprising a.

In the present invention, the process of forming the infrared sensing element,

Forming a reflective layer at at least one position on the lower substrate; Forming a sacrificial layer on the lower substrate to include the reflective layer; Removing the sacrificial layer and the lower substrate so that a part of the signal processor is opened on both sides of the reflective layer, and then forming a support part to be connected to the signal processor; Forming a support layer on the support and the sacrificial layer; Forming a sensing layer on the support layer at a position where the reflective layer is formed to be connected to the support part; Forming a protective layer on the sensing layer; Removing the sacrificial layer to open the electrode pad; And removing the sacrificial layer so that the sensing layer has a structure supported by the support in the space above the reflective layer. It is preferable to include.

In the present invention, a device wafer in which a signal processing circuit is integrated in a CMOS process and an infrared sensing unit made of MEMS technology in a monolithic manner are implemented using a system on a chip (SoC), and infrared rays on both sides The capped wafer formed with a filter is bonded and packaged in a vacuum at the device wafer and wafer level to realize an ultra-small infrared sensor that can significantly reduce the overall size.

In addition, in the present invention, since the infrared sensor for detecting a human body is implemented in a very small size, power consumption may be reduced and it may be efficiently managed.

In addition, since the infrared sensor for detecting a human body of the present invention is very small, the space occupied by the sensor is very insignificant, and thus its utilization is very large in small products having limited internal space such as mobile phones and laptops.

In addition, according to the present invention, by integrating an infrared sensing element for detecting a human body and a driving circuit of the infrared sensing element into a single chip (SoC), the size of the chip can be innovatively reduced and these configurations are monolithic on a single wafer. Due to the monolithic fabrication, the production cost and manufacturing time of chips can be significantly reduced.

In addition, according to the present invention, since the vacuum bonding at the wafer level bonds in a vacuum state, a heat sensitivity of the infrared sensing element is low, and thus a high sensitivity infrared sensor can be realized.

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

2 is a perspective view schematically showing an infrared sensor for detecting a human body according to an exemplary embodiment of the present invention.

As shown in FIG. 2, the infrared sensor 100 for detecting a human body according to an exemplary embodiment of the present invention includes a device wafer 110 and a cap wafer 120. That is, the device wafer 110 and the cap wafer 120 are bonded to each other in a vacuum atmosphere at the wafer level to form an individual infrared sensor 100 package.

The device wafer 110 includes at least one infrared ray sensing element 113, a support 115, and an electrode layer 117 formed on the lower substrate 111 on which the signal processor (not shown) is integrated. The infrared sensing element 113 serves to detect infrared rays, and the support unit 115 supports each infrared sensing element 113 to have a structure supported in the upper space of the lower substrate 111. In addition, the infrared sensing signal from each infrared ray sensing element 113 serves to transfer the signal processing unit. In addition, the signal processing unit detects the presence or absence of the human body by processing the detection signal from the infrared sensing element 113 according to a predetermined procedure. Preferably, the infrared sensing element 113 is arranged in M × N. Here, M and N are integers of 1 or more. In addition, the upper cap wafer 120 bonded to the element wafer 110 includes an upper substrate 121 having a cavity 123 formed on one surface thereof and an infrared filter 125 formed on at least one surface thereof.

In the drawing, the electrode 115 is open to the outside so as to be connected to an external electrode through wire bonding as an example. It may be connected to the bottom.

3 is a cross-sectional view of an infrared sensor for detecting a human body according to an exemplary embodiment of the present invention.

As shown in FIG. 3, the infrared sensor 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, wafer level packaging of the infrared sensing element is performed in a vacuum atmosphere. Therefore, the inside of the infrared sensing element package is in a vacuum state.

The device wafer 210 according to the present invention includes a lower substrate 211 in which the signal processor 212 is integrated in a predetermined circuit pattern, an infrared sensing element 213 formed on the lower substrate 211, and an external signal electrode (not shown). It comprises a electrode pad 214 connected to the). The lower substrate 211 may use a silicon substrate, but the present invention is not limited thereto. The signal processor 212 is preferably integrated into the lower substrate 211 through a CMOS (Complementary Metal-Oxide Semiconductor) process. In addition, the infrared sensing element 213 is manufactured by MEMS (Micro Electro Mechanical Systems) technology monolithically with the lower substrate 211 in which the signal processor 212 is integrated. Here, the signal processor 212 and the infrared sensing element 213 are characterized in that the lower substrate 211 is implemented as a System on a Chip (SoC).

The infrared sensing element 213 includes a reflective layer 215 formed on the lower substrate 211, a sensing layer 217 formed on the space 216 above the reflective layer 215, and a sensing layer 217. A support 218 supporting on the space 216. The support 218 serves to support the sensing layer 217 on the upper space 216 of the reflective layer 215 and electrically connects the sensing layer 217 and the signal processor 212 as described above. It plays a role of connecting. The support 218 preferably uses a conductive material.

In addition, the sensing layer 217 serves to detect infrared rays and has a floating structure floating on the upper space 216 of the reflective layer 215. The sensing layer 217 is preferably monolithically manufactured with the signal processor 212 using a micromachining technique. It is preferable to use a material such as VOx, a-Si, VWO _X as the sensing material of the sensing layer 217. In particular, in the case of using vanadium-tungsten oxide (VWO _X ), the vanadium-tungsten metal thin film is coated on an RF sputter and vanadium-tungsten is oxidized at a temperature of about 300 ° C. The size of the resistor can be adjusted according to the oxidation time, and a high TCR value of 3% or more can be obtained at a low resistance of 100 kΩ or less. In a preferred embodiment of the present invention, it is preferable to satisfy 0.5 ≦ _x ≦ 2 in VWO _X. Furthermore, in another embodiment of the present invention, vanadium oxide (V0 _x ) may be formed by depositing and heat-treating vanadium as a sensing material.

In addition, the reflective layer 215 is formed of a metal thin film to achieve a resonance effect by infrared reflection on the lower substrate 211. For example, it is preferably formed of aluminum or chromium / gold deposited to a thickness of approximately 2000 to 3000 mm 3.

Here, the space 216 formed between the reflective layer 215 and the sensing layer 217 has a structure in which the sensing layer 217 is supported on the space 216 so that the infrared sensing element 200 has a thermal isolation structure. To do this. This minimizes the heat loss caused by infrared incident, thereby improving the performance of the infrared sensor.

Meanwhile, in another embodiment of the present invention, a support layer 219a that selectively supports the sensing layer 217 in the air on the lower surface of the sensing layer 217 and an infrared sensing element on the sensing layer 217. A protective layer 219b may be further included to protect the entirety of 213. The support layer 219a and the protective layer 219b are preferably silicon nitride films each having a thickness of about 2000 microseconds. In addition, the sensing layer 217 and the support 218 may be directly connected to each other or may be connected through another conductive material.

The electrode pad 214 formed on the lower substrate 211 is for electrically connecting the signal processor 212 to an external signal electrode (not shown). The electrode pad 214 is connected to the signal processor 212 in the form of a metal thin film and serves to transfer a signal processed by the signal processor 212 to an external signal electrode. In an example of the present invention, the electrode pad 214 may optionally be connected to an external signal electrode through wire bonding. In another example, a through hole may be selectively formed in the lower substrate 211, and a through electrode connected to the electrode pad 214 may be formed on the inner surface of the through hole so as to be connected to an external signal electrode.

In addition, the cap wafer 220 according to the present invention has a cavity 222 formed therein, the upper substrate 221 bonded to the lower substrate 211, and at least one of an inner surface and an outer surface of the upper substrate 221. An infrared filter 223 formed on one surface, at least one getter 224 formed on an inner surface of the upper substrate 221, and a metal solder layer 225 for bonding the two substrates 211 and 221 to each other. Here, the metal solder layer 225 may be formed on the upper portion of at least one of the lower substrate 211 and the upper substrate 221. By using the metal solder layer 225 to bond the upper substrate 211 and the lower substrate 221 (infrared) sensor 200 is completed in the form of a package at the wafer level.

The cavity 222 formed on the inner surface of the upper substrate 221 is preferably formed to include the infrared sensing element 213 formed on the lower substrate 221. Infrared filters 223 are formed on at least one of an inner surface and an outer surface of the upper substrate 221, respectively. The infrared filter 223 serves to filter and transmit the wavelength emitted from the human body to be detected. For example, a person emits energy over the entire wavelength, but because it emits the most energy at a wavelength of 8-14 μm, it transmits the wavelength. In addition, one or more getters 224 are formed on an inner surface of the cavity 222. The getter 224 serves to increase the degree of vacuum inside the package by absorbing the gas generated during the bonding of 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 ^-6 torr. As the metal bonding method, thermocompression bonding, eutectic bonding, or the like may be used. As such, when the two substrates 211 and 221 are bonded together in a vacuum atmosphere, the infrared sensing element 213 may be located inside the vacuum package, and a plurality of infrared sensing elements 213 may be configured to implement the infrared sensor. Individual infrared sensing elements 213 protected by the upper substrate 221 may proceed without breaking the device in a subsequent dicing process.

As described above, the infrared sensor 200 of the present invention is implemented in a package form by bonding the device wafer 210 and the cap wafer 220 at the wafer level, and the inside of the package maintains a vacuum state. In addition, the infrared sensor 200 of the infrared sensor 200 is bonded to the device wafer 210 at the top such that the cap wafer 220 includes the infrared sensing device 213 supported in the air by the support 218 on the device wafer 210. The overall size can be greatly reduced. In the exemplary embodiment of the present invention, the infrared sensor 200 may be manufactured in a microminiature having a width of 0.5 mm to 2.0 mm, respectively, through the wafer level packaging process. In addition, unlike the prior art, since the upper portion is bonded to the upper portion using a wafer without using a cap housing, the height of the infrared sensor 200 may be manufactured to be extremely small, about 1 cm.

4 is a schematic diagram illustrating wafer level packaging of such an infrared sensor.

As shown in FIG. 4, in order to wafer-level package the infrared sensor 200 according to the present invention, the device wafer 210 and the cap wafer 220 are mounted by mounting the necessary devices through a separate process at the wafer level. To make. Subsequently, two wafers 210 and 220 are bonded to each other in a vacuum atmosphere through wafer bonding to be packaged. For example, it is preferable to bond and package in a vacuum chamber. This maintains a vacuum inside the package. The infrared sensor 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 sensor 200 may be completed by fabricating, bonding, and dicing a wafer at a wafer level through a predetermined semiconductor process.

Hereinafter, a method of manufacturing an ultra-small human body detecting infrared sensor according to the present invention will be described with reference to FIGS. 5 to 8.

5 and 6 are schematic diagrams showing a device wafer manufacturing method of the ultra-small human body sensing infrared sensor according to an embodiment of the present invention.

As shown in FIG. 5A, in order to manufacture an element wafer 310 of an infrared sensor according to an exemplary embodiment of the present invention, a lower substrate 311 in which a signal processor 312 is integrated in a CMOS process is first manufactured. To prepare. The lower substrate 311 is preferably an ASIC (Application Specific Integrated Circuit) semiconductor device manufactured through a general semiconductor manufacturing process. In this case, an electrode pad 313 connected to the signal processor 312 and the inside of the CMOS process is formed on the lower substrate 311. The electrode pad 313 is for transferring a signal from the signal processor 312 to an external signal electrode.

Next, in the present invention, as shown in Figure 5 (b), it is formed by patterning the reflective layer 314 at a predetermined position on the lower substrate 311. The reflective layer 314 is formed on the lower substrate 311 for the resonance effect by infrared reflection. The reflective layer 314 may be formed by depositing and patterning a metal thin film on the lower substrate 311 using a conventional photolithography process or a lift-off process.

Subsequently, as illustrated in FIG. 5C, the sacrificial layer 315 is formed on the lower substrate 311 including the reflective layer 314. The sacrificial layer 315 is for the levitation structure of the sensing layer 318, which will be described later, and may be formed by spin coating a polyimide material and performing heat treatment. However, the present invention is not limited thereto.

Next, in the present invention, as shown in FIGS. 5 (d) and 5 (e), the sacrificial layer 315 and the lower substrate where the part of the signal processor 312 is located so that a part of the signal processor 312 is opened. A hole 301 is formed in 311, and the support layer 316 is deposited on the sacrificial layer 315 including the inside of the hole 301. The support layer 316 supports the sensing layer 318 in the air at the lower surface of the sensing layer 318. The support layer 316 may be formed of a low stress silicon nitride film by using a low pressure chemical vapor deposition (LPCVD) method, a plasma enhanced chemical vapor deposition (PECVD) method, or the like.

Next, in the present invention, as shown in Fig. 5 (f), the support portion 317 is formed in the hole 301. The support part 317 supports the sensing layer 318 in the air so that the sacrificial layer 315 is removed in a subsequent process so that the sensing layer 318 has a floating structure in the air, and the signal processing unit 312 It is for electrically connecting the sensing layer 318. The support 317 is preferably formed by depositing a conductive material in the hole 301 or by filling the hole 301 with a conductive material.

Next, in the present invention, as illustrated in FIG. 5G, the sensing layer 318 is formed on the support layer 316 at the position where the reflective layer 314 is formed. It is preferable to use materials such as VO _x , a-Si, and VWO _X as the sensing material of the sensing layer 318. In addition, the sensing layer 318 may be manufactured through a conventional photolithography process on the support layer 316. As a result, the sensing layer 318 has a structure supported in the air by the support part 317, and further has a structure in which the support layer 316 is supported by the air at its lower surface for a safer structure.

Subsequently, the device wafer manufacturing method according to the present invention includes a protective layer 319 for protecting the infrared sensing element as a whole on the support layer 316, including the sensing layer 318, as shown in FIG. Form. In particular, the protective layer 319 is formed to protect the sensing layer 318 and the support 317.

Next, in the present invention, as shown in Fig. 6 (b), the support layer 316 and the protective layer 319 is patterned. That is, after the support layer 316 and the protective layer 319 are deposited, it is patterned according to the structure of the infrared sensing element. This removes the rest except for the infrared sensing element.

Next, in the present invention, as shown in FIG. 6C, the sacrificial layer 315 on the lower substrate 311 on which the electrode pad 313 is formed is removed such that the electrode pad 313 formed on the lower substrate 311 is opened. do. The removal process of the sacrificial layer 315 selectively opens the electrode pad 313 to connect the electrode pad 313 to the external signal electrode through wire bonding, and at the same time performs wafer bonding on the substrate 311. This is to form the metal solder layer 325.

Subsequently, in the present invention, as shown in FIG. 6 (d), the metal solder layer 325 is formed on the lower substrate 311. The metal solder layer 325 is formed to bond the lower substrate 311 and the upper substrate 321 to each other. In this case, the metal solder layer 325 may be formed on at least one of the lower substrate 311 and the upper substrate 321. The metal solder layer 325 preferably uses Au, AuSn, Sn, Cu, Ag, or the like as the bonding metal.

Next, in the present invention, as shown in FIG. At this time, when removing the sacrificial layer 315, it is preferable to remove using an oxygen plasma (O ₂ plasma) to prevent the friction (stiction) of the infrared sensing element.

As described above, in the device wafer 310 according to the exemplary embodiment of the present invention, the infrared sensing including the reflective layer 314, the protector 316, the support part 317, the sensing layer 318, and the protective layer 319 is provided. The device has a structure that is floated in space to minimize heat loss. To this end, the infrared sensing device according to the present invention is manufactured monolithically with the signal processor 312 on the device wafer 310 by using micromachining technology.

7 is a schematic view showing a cap wafer manufacturing method of the ultra-small human body sensing infrared sensor according to an embodiment of the present invention.

As shown in FIG. 7A, in order to manufacture the cap wafer 320 of the infrared sensor according to the present invention, first, a double-side polished upper substrate 321 is prepared, and then one surface of the upper substrate 321 is bulk-etched. A cavity 322 is formed. As the upper substrate 321, a silicon substrate is preferably used, but is not limited thereto. The cavity 322 is preferably formed at an appropriate height so as to include various components formed on the device wafer 310 described above. In an embodiment of the present invention, the cavity 322 is preferably formed to have a height of several tens of μm, and is preferably etched by KOH or reactive ion etching (ICP-RIE) after a known photolithography process.

Subsequently, as shown in FIG. 7B, an infrared filter 323 for transmitting specific infrared rays is formed on both sides of the upper substrate 321 formed in the cavity 322. The infrared filter 323 preferably uses a material such as Ge or ZnS. The infrared filter 323 selectively transmits an infrared wavelength to be detected on at least one of an outer surface and an inner surface of the upper substrate 321. For example, in order to detect the human body, preferably, an infrared wavelength of 8-14 μm is selectively transmitted.

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 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 to form the infrared sensing element as a package, and to maintain the degree of vacuum inside the packaging. It is desirable to form the metal material in the form of a thin film of approximately tens of nm. At this time, it is preferable to maintain a degree of vacuum of about 1 mtorr inside the packaging.

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 to bond the device wafer 310 and the cap wafer 320 at the wafer level to package the infrared wafer. The metal solder layer 325 preferably uses Au, AuSn, Sn, Cu, Ag, or the like as the bonding metal. More preferably, a material containing Au and Sn is used. Even more preferably, in one example of the present invention, the metal solder layer 325 may include Au 80wt% + Sn 20wt%, and in another example, Au 10wt% + Sn 90wt%. Here, Au and Sn may be deposited in a multilayer thin film form, or an alloy of Au and Sn may be deposited in a thin film form. The metal solder layer 325 formed of a multilayer thin film of Au and Sn may have a different thickness depending on the composition ratio. In the case of the Au and Sn alloy thin film, the metal solder layer 325 may have a thickness of 3 to 5 μm. In an embodiment of the present invention, it is preferable that the metal solder layer 325 uses a lift-off process.

As described above, the 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 one or more getters are formed on the infrared filter 323 formed in the cavity 322. The cap wafer 320 is fabricated at the wafer level in accordance with the present invention by forming the 324 and metal solder layer 325.

8 is a schematic diagram illustrating a bonding process between an element wafer and a cap wafer of an ultra-small human body detecting infrared sensor according to an exemplary embodiment of the present invention.

Referring to FIG. 8, the infrared sensor according to the present invention bonds the device wafer 310 and the cap wafer 320 manufactured in FIGS. 5 to 7 using various metal bonding methods in the vacuum chamber 81. For example, thermocompression bonding, eutectic bonding, or the like may be used as the metal bonding method. For example, the metal solder layer 325 may be bonded using Au-Au thermocompression bonding, Au-Sn eutectic bonding, or the like. In the above example, Au-Au thermocompression bonding may be pressurized and bonded using the plastic deformation of Au. In addition, when manufacturing the Au_Au metal solder layer 325, it is preferable to deposit Au by an electron-beam evaporator method, but may also be deposited by an electroplating method and an electroless plating method. In addition, the Au metal solder layer 325 for Au_Au thermocompression bonding is preferably a thin film having a thickness of 3 ~ 5㎛. At this time, the metal solder layer 325 for thermocompression bonding may be made of various metal compositions such as Au_Al, Cu_Cu, Au_Al. In addition, Au-Sn eutectic bonding using Au 80 wt% + Sn 20 wt% may be bonded by applying pressure at a relatively low temperature of 280 ° C., which is a eutectic temperature. The metal solder layer 325 capable of eutectic bonding may use various metal compositions such as Au_Si and Au_Ag. In a preferred embodiment of the present invention, Au_Au thermocompression bonding is preferable in view of low manufacturing cost of Au metal solder layer and simple process for thermocompression bonding.

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. The element wafer 310 and the cap wafer 320 are bonded by pressing at a constant pressure therefrom. At this time, the two wafers 310 and 320 are bonded by the metal solder layer 325.

At this time, heat and pressure during wafer bonding are caused by the diffusion of metal atoms and plastic deformation of the metal, and since the two elements are in a trade-off relationship, the bonding area and the shape of the metal solder layer, etc. The conditions are optimized according to the bonding environment. The reflow temperature for the joining is preferably 300 ° C. or lower, and the pressure is several MPa.

The infrared sensor packaged by wafer bonding as described above is individualized by dicing chip by chip. That is, after forming the output terminal of the infrared sensor for electrical connection to the external PCB and the like for each chip, the chip is diced using a dicing saw or the like. Such output terminals include, for example, a method of opening electrode pads for connection by wire bonding and a method of forming bumps in the form of flip chips on the back side of the device wafer. This will be described in detail below with reference to FIG. 8.

9 is a schematic diagram illustrating a signal electrode forming method of an ultra-small human body detecting infrared sensor 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. In the first method, as shown in FIG. 9 (a), after dicing the wafers of the device wafer 310 and the cap wafer 320, the dicing saw 91 is used to dice the package by individual chips, and then each chip. It is connected to an external signal electrode through a wire bonding 92 to electrode pads 313 formed at both ends of the wire.

In the second method, as shown in FIG. 8 (b), after the wafer bonding between the device wafer 310 and the cap wafer 320, the package is diced by individual chips using a dicing saw 91 and then the device wafer. A through hole 93 is formed from the rear surface of the 310 to the electrode pad 313. The through hole 93 may be formed by patterning using photoresist and then using deep reactive ion etching (DRIE). As an example, the through electrode 94 may be formed in the through hole 93 by using a plating method such as electroplating or electroless plating. As another example, the through electrode 94 may be formed by filling a metal material on the inner surface of the through hole 93. The through electrode 94 is preferably connected to the electrode pad 313 on the upper side and the solder bump 95 is formed on the lower side. The solder bumps 95 formed as described above may be electrically connected to a substrate such as a lower external PCB, thereby reducing a space for wire bonding as shown in FIG. 9 (a), which is more suitable for miniaturization of a product. The through electrode 94 may be Au, Cu, Ni, NiCr, etc., but the present invention is not limited thereto.

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.

As portable products such as mobile phones, PDAs, and MP3 players, which are widely used in recent years, have become smaller and lighter, devices mounted on these products are also becoming smaller. In line with this trend, efforts have been made to manufacture a miniature infrared sensor for human body detection.

From this point of view, in the infrared sensor according to the present invention, the infrared sensing element and the signal processing unit are implemented as SoC, and the size of the infrared sensor can be minimized by vacuum bonding at the wafer level. Since the output terminal for connection is formed of solder chip of flip chip type, it can be manufactured in the small size of less than 2mm in width and length.

In addition, the infrared sensor of the present invention includes a signal processing unit, an infrared sensing element made of MEMS, and an infrared filter on a substrate, and since these components are all made at the wafer level, the cost of packaging that takes up a large part of the production cost of the infrared sensor is increased. This breakthrough significantly reduces the production cost of the sensor and is suitable for high volume production.

Since the infrared sensor is very small in size, there is almost no limitation in application space, the power consumption is very low due to the characteristics of the MEMS device, and after detecting the human body, it is possible to efficiently manage the power consumption of the entire system. It can be used as a means to save the power of the whole system.

Due to these advantages and features, the infrared sensor for detecting a human body according to the present invention can be very usefully applied to various industrial fields.

1 is a schematic view showing a manufacturing process of a conventional bolometer-type infrared sensor.

2 is a perspective view schematically showing an infrared sensor for detecting a human body according to an exemplary embodiment of the present invention.

3 is a cross-sectional view of an infrared sensor for detecting a human body according to an exemplary embodiment of the present invention.

4 is a schematic diagram illustrating wafer level packaging of such an infrared sensor.

5 is a schematic diagram illustrating a device wafer manufacturing method of the ultra-small human body sensing infrared sensor according to an embodiment of the present invention.

Figure 6 is a schematic diagram showing a cap wafer manufacturing method of the ultra-small human body sensing infrared sensor according to an embodiment of the present invention.

7 is a schematic diagram illustrating a bonding process between an element wafer and a cap wafer of an ultra-small human body detecting infrared sensor according to an exemplary embodiment of the present invention.

8 is a schematic diagram illustrating a signal electrode forming method of an ultra-small human body sensing infrared sensor 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

111,211,311: Lower board 121,221,321: Upper board

212,312: signal processor 214,313: electrode pad

215,314 Reflective layer 217,317 Sensing layer

218,319 Support portion 225,325 Metal solder layer

Claims (22)

A lower substrate in which a signal processing unit is integrated through a CMOS process; At least one infrared sensing element formed on the lower substrate and electrically connected to the signal processor; An upper substrate having a cavity formed on one surface and bonded at a wafer level on the lower substrate such that each of the infrared sensing elements is included in the cavity; An infrared filter formed on at least one surface of the upper substrate; A getter formed in the cavity to absorb the gas released during the bonding; A metal solder layer for bonding the upper substrate and the lower substrate; And An electrode pad formed on the lower substrate to electrically connect the signal processor with an external electrode; Including, The inside of the bonded upper substrate and the lower substrate is a micro-infrared sensor for human body detection, characterized in that the vacuum state. The method of claim 1, wherein each of the infrared sensing element, A reflective layer formed on the lower substrate; A sensing layer formed on a space above the reflective layer; A support layer formed on a lower surface of the sensing layer to support the sensing layer; A protective layer formed on an upper surface of the sensing layer; And A supporter for supporting the sensing layer such that the sensing layer has a structure supported on the space; Ultra-small human body detection infrared sensor comprising a. The method of claim 2, The sensing layer is a miniature human-sensing infrared sensor, characterized in that it comprises an infrared sensing film made of a material selected from VOx, a-Si, VWO _X. The method of claim 1, wherein each of the infrared sensing element, The ultra-small human body sensing infrared sensor, characterized in that formed on the lower substrate as a monolithic (SoC) system and a signal processor. The method of claim 1, The lower substrate has at least one through hole having a through electrode formed therein, and the through electrode is connected to the electrode pad at an upper portion of the ultra-small human body sensing infrared sensor, characterized in that a solder bump is formed at the bottom. The method of claim 1, The electrode pad is an ultra-small human body sensing infrared sensor, characterized in that connected by an external signal electrode and wire bonding. The method of claim 1, The infrared filter is an ultra-small human body sensing infrared sensor, characterized in that the transmission of light of 8 ~ 14㎛ wavelength. The method of claim 1, The getter is a miniature human body infrared sensor characterized in that the deposition is made in a thin film form of a Ti material. The method of claim 1, The metal solder layer is an ultra-small human body sensing infrared sensor, characterized in that it comprises at least one material selected from Au, Sn, AuSn, Cu, Si. 10. The method of claim 9, The metal solder layer is an ultra-small human body sensing infrared sensor, characterized in that containing a material of Au 80wt% + Sn 20wt%. The method of claim 10, The metal solder layer is ultra-small human body sensing infrared sensor, characterized in that the thickness has a range of 3 ~ 5㎛. The method of claim 11, The metal solder layer is a miniature human body infrared sensor characterized in that it comprises Au_Au solder. delete The method according to any one of claims 1 to 12, Ultra-thin human body sensing infrared sensor, characterized in that the length of the horizontal and vertical length of the upper substrate and the lower substrate, respectively 0.5 ~ 2.0mm. Providing a device wafer and a cap wafer, respectively; Bonding the device wafer and the cap wafer at a wafer level in a vacuum atmosphere to form a package; And Dicing the package into individual chips; Including The process of preparing the device wafer, Integrating a predetermined signal processor on the lower substrate through a CMOS process; Forming electrode pads electrically connected to the signal processor at both ends of the lower substrate; Forming at least one infrared element for sensing a human body using a system on a chip (SoC) monolithically with the signal processor on the lower substrate; And Forming a metal solder layer at a predetermined position of the lower substrate; Including, The process of preparing the cap wafer, Providing an upper substrate having a cavity formed on one surface thereof; Forming an infrared filter on at least one surface of the upper substrate; Forming a getter on an inner surface of the upper substrate on which the cavity is formed; And Forming a metal solder layer at a predetermined position of the upper substrate; Method of manufacturing an ultra-small human body detection infrared sensor comprising a. The method of claim 15, wherein forming the infrared sensing element, Forming a reflective layer at at least one position on the lower substrate; Forming a sacrificial layer on the lower substrate to include the reflective layer; Removing the sacrificial layer and the lower substrate so that a part of the signal processor is opened on both sides of the reflective layer, and then forming a support part to be connected to the signal processor; Forming a support layer on the support and the sacrificial layer; Forming a sensing layer on the support layer at a position where the reflective layer is formed to be connected to the support part; Forming a protective layer on the sensing layer; Removing the sacrificial layer to open the electrode pad; And Removing the sacrificial layer such that the sensing layer has a structure supported by the support in the space above the reflective layer; Method of manufacturing an ultra-small human body detection infrared sensor comprising a. The method of claim 15, wherein the bonding of the upper substrate and the lower substrate, 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 method selected from thermocompression bonding or eutectic bonding; Method of manufacturing an ultra-small human body detection infrared sensor comprising a. The method of claim 15, The cavity of the upper substrate is a method of manufacturing a miniature human body infrared sensor characterized in that the etching using a KOH solution. The method of claim 15, The getter is a method of manufacturing an ultra-small human body sensing infrared sensor, characterized in that for depositing a Ti metal material in the form of a thin film by using any one of the method of sputter deposition or ion beam deposition. The method of claim 15, wherein after the bonding of 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 an electrode layer; Method of manufacturing an ultra-small human body detection infrared sensor, characterized in that it further comprises. 21. The method of claim 20, The through hole is a manufacturing method of the ultra-small human body detection infrared sensor, characterized in that formed using the DRIE method. The method of claim 15, After the process of bonding the device wafer and the cap wafer, Connecting the electrode pad to the external signal electrode by wire bonding in the device wafer; Method of manufacturing an ultra-small human body detection infrared sensor, characterized in that it further comprises.

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