KR102554847B1 - Thermal-based infra-red source - Google Patents

Abstract

Board; a heater spaced apart from the substrate; a membrane supporting the heater; a membrane support for fixing the membrane to the substrate; and an air gap between the membrane and the substrate.

Description

Thermal infrared source {Thermal-based infra-red source}

The present invention relates to a thermal infrared source, and more particularly, to a thermal-based infrared source using microelectromechanical integration system (MEMS) technology.

Recently, various types of infrared sensors have been studied in various fields including the Internet of Things (IoT), and some of them have been commercialized and are actually applied to various products.

Infrared is a kind of electromagnetic wave whose wavelength is 0.75 um to 1000 um larger than visible light. When the wavelength is less than a few μm, it is called near infrared rays, and when the wavelength is 25 μm or more, it is classified as far infrared rays, and between them is classified as mid-infrared rays.

All objects with a temperature above absolute zero have a natural frequency due to the vibration of atoms, and they emit black body radiation according to Plank's law. Dense objects such as solids emit radiation in the form of a continuous spectrum, and the total amount of radiation is proportional to the fourth power of temperature according to the Stefan-Boltzmann equation.

Infrared rays are also called heat rays because they contain heat, and thermal action is also a characteristic of infrared rays. When a material absorbs near-infrared rays, the movement of particles in the material becomes active, and the temperature rises.

The infrared sensor may include a light emitting unit emitting light of a certain frequency and a light receiving unit receiving light emitted from the light emitting unit. Infrared rays generated by the light emitting unit collide with an object and are reflected, and the light receiving unit may detect the presence or absence of an object or the distance to the object by detecting the reflected light.

The problem to be solved by the present invention is to provide a compact surface-processing thermal infrared source that is simple in process, capable of high-output driving, and mechanically stable.

An object to be solved by the present invention is to provide a subminiature thermoelectric infrared source capable of providing services in various environments.

The problem to be solved by the present invention is not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description below.

In order to achieve the above object, a thermal infrared source according to an embodiment of the present invention includes a substrate; a heater spaced apart from the substrate; a membrane supporting the heater; a membrane support for fixing the membrane to the substrate; and an air gap between the membrane and the substrate.

Details of other embodiments are included in the detailed description and drawings.

According to the thermal infrared source according to an exemplary embodiment of the present invention, the complicated double-sided process can be simplified because the process is performed only on the top of the substrate through the MEMS-based surface processing method.

According to the thermal infrared source according to an exemplary embodiment of the present invention, since the infrared selective filter is manufactured through an integrated semiconductor process, the process can be simplified and furthermore, it can be miniaturized.

According to the thermal infrared source according to an exemplary embodiment of the present invention, it is manufactured in a small size and installed in various systems (IoT sensor nodes or portable terminals) to provide various services.

According to the thermal infrared source according to an exemplary embodiment of the present invention, it is possible to provide a mechanically stable structure by fixing the infrared sensing part to the substrate through the membrane support to improve the reliability of external shock or drop.

According to the thermal infrared source according to an exemplary embodiment of the present invention, it has a mechanically stable structure and can be easily applied to a portable terminal.

According to the thermal infrared source according to an exemplary embodiment of the present invention, since a reflector is disposed on a substrate insulator with an air gap therebetween, output loss can be suppressed.

According to the thermal infrared source according to an exemplary embodiment of the present invention, it can be used for a long time due to low power characteristics.

1 is a perspective view illustrating a thermal infrared source according to an exemplary embodiment of the present invention.
FIG. 2 is a cross-sectional view of a thermal infrared source according to an exemplary embodiment of the present invention taken along line AA′ of FIG. 1 .
FIG. 3 is a cross-sectional view taken along line BB′ of FIG. 1 of a thermal infrared source according to an exemplary embodiment of the present invention.
4 to 8 are cross-sectional views illustrating a method of manufacturing a thermal infrared source according to an exemplary embodiment of the present invention.

In order to sufficiently understand the configuration and effects of the technical idea of the present invention, preferred embodiments of the technical idea of the present invention will be described with reference to the accompanying drawings. However, the technical idea of the present invention is not limited to the embodiments disclosed below, and may be implemented in various forms and various changes may be made. However, it is provided to complete the disclosure of the technical idea of the present invention through the description of the present embodiments, and to completely inform those skilled in the art of the scope of the invention to which the present invention belongs.

Parts designated with like reference numerals throughout the specification indicate like elements. Embodiments described herein will be described with reference to block diagrams, perspective views, and/or cross-sectional views, which are ideal illustrations of the technical idea of the present invention. In the drawings, the thickness of regions is exaggerated for effective description of technical content. Accordingly, the regions illustrated in the drawings have schematic properties, and the shapes of the regions illustrated in the drawings are intended to illustrate a specific shape of a region of a device and are not intended to limit the scope of the invention. Although various terms are used to describe various elements in various embodiments of the present specification, these elements should not be limited by these terms. These terms are only used to distinguish one component from another. Embodiments described and illustrated herein also include complementary embodiments thereof.

Terms used in this specification are for describing embodiments and are not intended to limit the present invention. In this specification, singular forms also include plural forms unless specifically stated otherwise in a phrase. The terms 'comprises' and/or 'comprising' used in the specification do not exclude the presence or addition of one or more other elements.

Hereinafter, the present invention will be described in detail by describing preferred embodiments of the technical idea of the present invention with reference to the accompanying drawings.

The infrared sensor light emitting unit may be classified into an IR laser, an IR LED (Light Emitting Diode), and a thermal device. The IR laser may have high output power and excellent directivity. IR lasers can be expensive. IR LEDs can have relatively low output. IR LEDs can be price competitive. IR LEDs are recently used in infrared sensors.

Thermal elements may be classified into micro-bulb, black-body, MEMS, and the like. Thermal elements may have lower output power and directivity than lasers or LEDs, and may have a wide spectrum. An infrared filter may be applied to the thermal element. The thermal element can be implemented at low cost. Thermal elements can be easily applied to IoT applications.

The thermal infrared source can be fabricated in a miniature form using a microelectro-mechanical system (MEMS) process to form a thermally isolated localized micro-heater.

A MEMS-based thermal infrared source may be fabricated through a MEMS process using a semiconductor fabrication process. The MEMS-based thermal infrared source can emit infrared rays in a wide spectrum by applying electric energy to a micro-heater having a line width of several μm.

The MEMS-based thermal infrared source can be divided into a bulk micromachined-type source for processing both sides of a substrate and a surface micromachined-type source for processing only an upper portion of a substrate.

The MEMS-based bulk processing type thermal infrared source may have a complicated process because both sides of the substrate must be processed simultaneously. The MEMS-based bulk processing type thermal infrared source may have a structure in which a substrate portion under a membrane including a micro-heater is removed to minimize heat loss. Bulky thermal infrared sources may be structurally vulnerable to impact. Bulk processing type thermal infrared sources may have limitations in application to IoT sensor nodes or portable terminals.

Since the MEMS-based surface-processed source has a structure in which only a portion of the lower portion of the membrane is etched from the upper portion of the substrate, the process can be simplified. MEMS-based surface-processed sources can be easily mass-produced. In the active region, the substrate of the surface-processing type source may be maintained at a uniform thickness, unlike a structure in which the entire substrate portion under the membrane is removed in the bulk processing type source. The surface-processed source may have excellent drop reliability.

The MEMS-based surface-processed thermal infrared source can be fabricated with a simple process, has excellent output efficiency, and is mechanically stable. The MEMS-based surface-processed thermal infrared source can be mounted on an IoT sensor node or a portable terminal and used for various services.

1 is a perspective view illustrating a thermal infrared source according to an exemplary embodiment of the present invention. FIG. 2 is a cross-sectional view taken along A-A' of FIG. 1 to show a thermal infrared source according to an exemplary embodiment of the present invention. FIG. 3 is a cross-sectional view taken along line BB′ of FIG. 1 to show a thermal infrared source according to an exemplary embodiment of the present invention.

1 and 2, a thermal infrared source 1 according to an exemplary embodiment of the present invention converts a substrate 10, a substrate insulator 11 formed on the substrate 10, and electrical energy into thermal energy. Heater 31 and heater metal 30 for emitting infrared rays, heater insulator 32 for electrically insulating the heater 31, and preventing heat energy from being lost to the substrate 10 or the substrate insulator 11 A membrane 20 supporting the reflector 12, the heater 31 and the heater metal 30, a membrane support 22 supporting the membrane 20 on the substrate insulator 11, and a metamaterial constituting the infrared filter. A metal pattern 40 and a meta-material insulator 41 may be included.

According to an exemplary embodiment, the substrate 10 may be a silicon substrate used in a general semiconductor process. According to an exemplary embodiment, the substrate 10 may be doped with quartz, gallium-nitrogen (GaN), or gallium-arsenic (GaAs). According to an exemplary embodiment, the substrate 10 may be formed of another material capable of fixing the heater 31 or the like.

A substrate insulator 11 may be positioned over the substrate 10 . The substrate insulator 11 may be formed of an insulating material. The substrate insulator 11 may electrically insulate the substrate 10 from the rest of the components.

The heater 31 may emit infrared rays by generating thermal energy proportional to applied electrical energy. The heater 31 may have electrical resistance. The heater 31 may generate Joule heat when electricity is applied.

Referring to FIG. 3 , the heater 31 may be formed on the membrane 20, and may preferably have a width of several μm. However, the arrangement of FIG. 3 is exemplary and is not limited thereto. The heater 31 may be arranged in another structure capable of efficiently generating Joule heat and emitting infrared rays.

The heater metal 30 may have a function of being connected to the heater 31 to supply electrical energy. The heater metal 30 may include heater pads 31a and 31b. Electric energy may be supplied to the heater metal 30 through the heater pads 31a and 31b.

The heater 31 and/or the heater metal 30 may be formed of metal or conductive metal oxide. According to an exemplary embodiment, the heater 31 and/or the heater metal 30 may be formed of platinum (Pt), aluminum (Al), gold (Au), or the like. The heater 31 and/or the heater metal 30 may be formed by a sputtering deposition method, an electron beam deposition method, or a vapor deposition method.

The heater insulator 32 may cover part or all of the heater 31 and the heater metal 30 . The heater insulator 32 may electrically insulate a portion of the heater 31 and the heater metal 30 from other components.

The membrane 20 may support the heater 31 and/or the heater metal 30 and the like. The membrane 20 may have an electrical insulating function. The membrane 20 may be formed using an insulator. Membrane 20 may be formed of a single or multiple polymer insulating material, silicon oxide film or silicon nitride film.

A membrane support 22 may be positioned below the membrane 20 . The membrane support 22 may support the membrane 20 . The membrane support 22 may fix the membrane 20 to the substrate insulator 11 or the substrate 10 . The membrane support 22 can improve structural problems that may occur in the event of a drop impact. The membrane support 22 can improve mechanical reliability. The thermal infrared source 1 is manufactured in a MEMS-based surface processing type and can be mechanically stable against external impact.

An air gap 50 may exist between the membrane 20 and the substrate insulator 11 . Air may be located in the air gap 50 . Air may have a low thermal conductivity. Loss of heat generated from the heater 31 or the like to the substrate 10 or the like due to the air gap 50 can be minimized. The output of the thermal infrared source 1 can be enhanced. The efficiency of the thermal infrared source 1 can be improved.

In order to form the air gap 50, an arbitrary solid sacrificial layer (21, see FIGS. 5 to 7) having a certain thickness is formed between the membrane 20 and the substrate insulator 11, and the membrane 20, the heater (31), the heater insulator 32, the meta-material metal pattern 40, and the meta-material insulator 41 are laminated, and then the sacrificial layer can be removed by surface processing. An air gap 50 may be formed in a space where the sacrificial layer 21 is removed. Heat loss can be minimized by the air gap 50 .

A reflector 12 may be disposed on the substrate insulator 11 . In an exemplary embodiment, the reflector 12 may include metal. The reflector 12 may reflect radiant heat directed toward the substrate 10 among the energy generated by the heater 31 . The reflector 12 can prevent energy from being lost. The reflector 12 can improve the output of infrared rays.

The metamaterial metal pattern 40 may be implemented through a structure using a surface plasmon resonance (SPR) phenomenon. The meta-material metal pattern 40 may be manufactured through a semiconductor process. This process can simplify the manufacturing process. The metamaterial metal pattern 40 may be designed to select a specific wavelength range using a semiconductor process. When the metamaterial metal pattern 40 is appropriately disposed, a filter passing only a desired wavelength band can be implemented.

The metamaterial insulator 41 may cover the metamaterial metal pattern 40 . The meta-material insulator 41 may electrically insulate the meta-material metal pattern 40 from other materials. The metamaterial insulator 41 may be formed of a silicon film or a silicon nitride film. The metamaterial insulator 41 may be manufactured using a thermal oxidation deposition method, a sputtering deposition method, or a chemical vapor deposition method.

The thermal infrared source fabricated through the MEMS-based surface processing process can be collectively fabricated on the top of the structure. The thermal infrared source may be batch fabricated from metal and insulator through a CMOS foundry service. Thermal infrared sources can be relatively cost competitive.

The MEMS-based surface-processed thermal infrared source according to an exemplary embodiment of the present invention can be simply manufactured by processing only the upper portion of the substrate. The thermal infrared source can secure mechanical stability against sudden external impact by means of the membrane support 22 . The thermal infrared source can improve output efficiency by minimizing heat lost to the substrate 10 by the reflector 12 . Since the thermal infrared source is manufactured by the MEMS-based surface processing method, the etching process of the substrate 10 is not included, and thus the manufacturing process can be simplified.

4 to 8 are cross-sectional views sequentially showing a method of manufacturing a thermal infrared source.

Referring to FIG. 4 , a substrate insulator 11 may be laminated on the substrate 10 to electrically insulate the substrate 10 from the rest of the components. An output efficiency may be improved by stacking a reflector 12 on the substrate insulator 11 .

Referring to FIG. 5 , a membrane support 22 may be disposed on the substrate insulator 11 so that the membrane 20 may be fixed to the substrate 10 or the substrate insulator 11 . In addition, a sacrificial layer 21 having a predetermined thickness may be formed on the substrate insulator 11 and/or the reflector 12 . A membrane 20 may be stacked on the membrane support 22 and the sacrificial layer 21 . The sacrificial layer 21 may be removed in a final process to form an air gap 50 in place of the sacrificial layer 21 . The air gap 50 may minimize infrared rays lost to the substrate 10 .

Referring to FIG. 6 , a heater metal 30 and a heater 31 may be stacked on top of the membrane 20 formed on the sacrificial layer 21 . In order to apply input power to the inside, heater pads 31a and 31b may be formed at the edges. The heater 31 and/or the heater metal 30 may be formed by a sputtering deposition method, an electron beam deposition method, or a vapor deposition method. Next, in order to electrically insulate the heater 31, a heater insulator 32 may be formed surrounding a portion of the heater 31 and/or the heater metal 30.

Referring to FIG. 7 , a metamaterial metal pattern 40 capable of selecting infrared rays and a metamaterial insulator 41 may be formed on a heater insulator 32 using a semiconductor process. The metamaterial insulator 41 may be manufactured using a thermal oxidation deposition method, a sputtering deposition method, or a chemical vapor deposition method.

Referring to FIG. 8 , the sacrificial layer 21 made of an insulating material may be removed. According to an exemplary embodiment, the sacrificial layer 21 may be removed through a MEMS-based semiconductor process. An air gap 50 may be formed in a position where the sacrificial layer 21 is removed. Air may be located in the air gap 50 . Air may have a low thermal conductivity. A thermal infrared source in which the sacrificial layer 21 is replaced with the air gap 50 can reduce heat loss.

Although the embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art can implement the present invention in other specific forms without changing the technical spirit or essential features. You will understand that there is Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive.

1: thermal infrared source
10: substrate
11: board insulator
12: reflector
20: membrane
21: sacrificial layer
22: membrane support
30: heater metal
31: heater
31a: heater pad
31b: heater pad
32: heater pad insulator
40: metamaterial metal pattern
41: metamaterial insulator
50: air gap

Claims (10)

Board;
a heater spaced upward from the substrate;
a membrane supporting the heater;
a membrane support for fixing the membrane to the substrate;
an air gap between the membrane and the substrate;
a substrate insulator on the substrate; and
a reflector on the substrate insulator; Including,
The thermal infrared source of claim 1 , wherein the reflector is disposed under the air gap between the substrate insulator and the heater. According to claim 1,
The thermal infrared source further comprises a heater metal connected to the heater to supply electric energy to the heater. According to claim 2,
and a heater insulator covering at least a portion of the heater and the heater metal. According to claim 3,
A thermal infrared source further comprising a metamaterial metal pattern on the heater insulator. According to claim 4,
A thermal infrared source further comprising a metamaterial insulator covering the metamaterial metal pattern. delete delete delete delete delete

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