KR102640117B1 - Infrared sensor - Google Patents

Abstract

A substrate, a support film disposed on the substrate and spaced apart from the substrate, a first thermoelectric element and a second thermoelectric element spaced apart from each other on the support film in a direction parallel to the upper surface of the substrate, and the first thermoelectric element on the support film. An infrared sensor is provided including a connection electrode connecting one end of the element and one end of the second thermoelectric element, and an infrared filter disposed on the first and second thermoelectric elements, wherein the first and second thermoelectric elements include The infrared filter may include semiconductor materials of different conductivity types, and may include metal patterns periodically formed at intervals smaller than the wavelength of an electromagnetic wave in the infrared band incident on the infrared filter.

Description

Infrared sensor {INFRARED SENSOR}

The present invention relates to an infrared sensor, and more specifically to an infrared sensor using MEMS technology.

In general, thermoelectric elements including thermoelectric conversion elements have a p-n junction pair structure in which a p-type thermoelectric material and an n-type thermoelectric material are joined. When a metal wire is connected to both ends of such a p-n junction pair to heat one side of the thermoelectric material and keep the other side cool, a voltage due to the temperature difference between both ends, that is, thermo electromotive force, is generated, forming a closed circuit. Current can flow in. This is called the Seebeck effect, and is the principle of thermoelectric power generation by thermoelectric elements or infrared sensors.

Recently, MEMS (Micro Electro Mechanical System) sensors manufactured using semiconductor technology have been attracting attention due to their miniaturization, low price, and high performance.

The problem to be solved by the present invention is to provide an infrared sensor with improved structural stability.

Another problem to be solved by the present invention is to provide an infrared sensor with improved sensitivity.

Another problem that the present invention aims to solve is to provide an infrared sensor with a simplified manufacturing process.

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.

An infrared sensor according to embodiments of the present invention for solving the above-mentioned technical problems includes a substrate, a support film disposed on the substrate and spaced apart from the substrate, and a support film spaced apart from each other in a direction parallel to the upper surface of the substrate on the support film. a first thermoelectric element and a second thermoelectric element, a connection electrode connecting one end of the first thermoelectric element and one end of the second thermoelectric element on the support membrane, and infrared rays disposed on the first and second thermoelectric elements. Can contain filters. The first and second thermoelectric elements may include semiconductor materials of different conductivity types. The infrared filter may include metal patterns periodically formed at intervals smaller than the wavelength of an electromagnetic wave in the infrared band incident on the infrared filter.

The infrared sensor according to embodiments of the present invention can transmit infrared rays incident from the outside to the first and second thermoelectric elements with high efficiency, and the sensitivity of the infrared sensor can be improved.

Additionally, an empty space may be provided between the first and second thermoelectric elements and the substrate. Accordingly, heat incident to the infrared sensor can be prevented from leaking through the substrate, and the sensitivity of the infrared sensor can be improved.

In addition, the structural stability of the infrared sensor can be improved by supporting the center of the support film spaced from the substrate through the second support part.

1 is a perspective view for explaining an infrared sensor according to embodiments of the present invention.
Figure 2 is a plan view for explaining an infrared sensor according to embodiments of the present invention.
Figure 3 is a cross-sectional view for explaining an infrared sensor according to embodiments of the present invention.
Figure 4 is a plan view for explaining an infrared filter.
Figure 5 is a plan view for explaining an infrared sensor according to embodiments of the present invention.
6 and 7 are cross-sectional views for explaining an infrared sensor according to embodiments of the present invention.
Figure 8 is a plan view for explaining an infrared sensor according to embodiments of the present invention.
Figure 9 is a cross-sectional view for explaining an infrared sensor according to embodiments of the present invention.
10 to 14 are cross-sectional views for explaining a method of manufacturing an infrared sensor according to embodiments of the present invention.

In order to fully understand the configuration and effects of the present invention, preferred embodiments of the present invention will be described with reference to the attached drawings. However, the present invention is not limited to the embodiments disclosed below, and can be implemented in various forms and various changes can be made. However, the description of the present embodiments is provided to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the present invention of the scope of the invention. Those of ordinary skill in the art will understand that the inventive concepts can be practiced in any suitable environment.

The terminology used herein is for describing embodiments and is not intended to limit the invention. As used herein, singular forms also include plural forms, unless specifically stated otherwise in the context. As used in the specification, 'comprises' and/or 'comprising' refers to the presence of one or more other components, steps, operations and/or elements. or does not rule out addition.

In this specification, when a film (or layer) is referred to as being on another film (or layer) or substrate, it may be formed directly on the other film (or layer) or substrate, or may form a third film (or layer) between them. or layer) may be interposed.

In various embodiments of the present specification, terms such as first, second, third, etc. are used to describe various regions, films (or layers), etc., but these regions and films should not be limited by these terms. do. These terms are merely used to distinguish one region or film (or layer) from another region or film (or layer). Accordingly, a film quality referred to as a first film quality in one embodiment may be referred to as a second film quality in another embodiment. Each embodiment described and illustrated herein also includes its complementary embodiment. Parts indicated with the same reference numerals throughout the specification represent the same elements.

Unless otherwise defined, terms used in the embodiments of the present invention may be interpreted as meanings commonly known to those skilled in the art.

Hereinafter, an infrared sensor according to the concept of the present invention will be described with reference to the drawings.

1 is a perspective view for explaining an infrared sensor according to embodiments of the present invention. Figure 2 is a plan view for explaining an infrared sensor according to embodiments of the present invention, and some components are omitted to describe the first and second thermoelectric elements in detail. FIG. 3 is a cross-sectional view illustrating an infrared sensor according to embodiments of the present invention, taken along line A-A' of FIGS. 1 and 2.

Referring to FIGS. 1, 2, and 3, a substrate 100 may be provided. The substrate 100 may include silicon (Si) or a compound semiconductor. For example, the substrate 100 may include a group III-V compound semiconductor material such as gallium nitrogen (GaN), gallium arsenide (GaAs), or indium phosphorus (InP). Alternatively, the substrate 100 may include quartz.

A substrate insulating layer 110 may be disposed on the substrate 100. The substrate insulating layer 110 may cover the upper surface of the substrate 100. When the substrate 100 is made of silicon (Si), the substrate insulating layer 110 may include silicon oxide or silicon nitride. Alternatively, the substrate insulating layer 110 may include an organic material.

A support film 200 may be disposed on the substrate insulating layer 110. Specifically, the support film 200 may be spaced upward from the substrate insulating layer 110 . For example, the distance between the support film 200 and the upper surface of the substrate insulating layer 110 may be 1 μm to 20 μm. As a result, an empty space AS may be defined between the substrate insulating layer 110 and the support film 200. From a plan view, the support membrane 200 may have a generally circular shape, but embodiments of the present invention are not limited thereto. Unlike shown, the support membrane 200 may have various planar shapes, such as a square shape or a polygonal shape. The support membrane 200 may include a material with high thermal and electrical resistance. The support film 200 may include a polymer insulating material, silicon oxide (SiO _x ), or silicon nitride (SiN _x ).

The support film 200 may be supported and fixed on the substrate 100 by the first supports 210 . For example, the first supports 210 include a first part 212 extending from the outer surface of the support film 200 toward the substrate 100, and a first part 212 in contact with the substrate insulating layer 110. It may include a second portion 214 extending from one end of the substrate onto the upper surface of the substrate insulating layer 110 . The first support parts 210 may be respectively connected to both ends of the support membrane 200 . The first supports 210 may include the same material as the support membrane 200 .

The second support part 220 may be disposed in the empty space AS between the substrate insulating layer 110 and the support film 200. For example, the second support part 220 may be disposed on the upper surface of the substrate insulating layer 110, and may extend toward the lower surface of the support film 200 and come into contact with the support film 200. That is, the second support part 220 may be provided on the substrate insulating layer 110 to support the center of the support film 200. The second support portion 220 may have a cylindrical shape. Although FIG. 3 shows that one second support part 220 is provided, the present invention is not limited thereto, and a plurality of second support parts 220 may be provided. The second support portion 220 may include the same material as the support membrane 200.

A first thermoelectric element 310 and a second thermoelectric element 320 may be disposed on the support membrane 200. One side of the first thermoelectric element 310 and one side of the second thermoelectric element 320 are disposed to face the center of the support membrane, and the other sides of the first and second thermoelectric elements 310 and 320 are disposed to face the outer portion of the support membrane. You can. The first thermoelectric element 310 and the second thermoelectric element 320 may be spaced apart from each other in a direction parallel to the upper surface of the support membrane 200. Preferably, the first thermoelectric element 310 and the second thermoelectric element 320 may be located above the empty space AS between the substrate 100 and the support film 200. The first thermoelectric element 310 and the second thermoelectric element 320 may form a thermocouple. As an example, the first thermoelectric element 310 and the second thermoelectric element 320 may be connected in series, and the ends where the first thermoelectric element 310 and the second thermoelectric element 320 are connected are hot junctions. You can have Preferably, the thermal contact point between the first thermoelectric element 310 and the second thermoelectric element 320 may be located on the center of the support membrane 200. The first thermoelectric element 310 and the second thermoelectric element 320 may include semiconductors of different conductivity types. As an example, the first thermoelectric device 310 may include an n-type semiconductor, and the second thermoelectric device 320 may include a p-type semiconductor.

The first thermoelectric element 310 and the second thermoelectric element 320 may be connected through the first connection electrode 330. As an example, the first connection electrode 330 may be provided on the support membrane 200 and contact one end of the first thermoelectric element 310 and one end of the second thermoelectric element 320. The first connection electrode 330 may include a metal such as platinum (Pt), aluminum (Al), or gold (Au), or a conductive metal oxide.

The first thermoelectric element 310 is connected to the first pad 312 provided on one of the second parts 214 of the first supports 210, and the second thermoelectric element 320 is connected to the first support part 320. It may be connected to a second pad 322 provided on the other second part 214 of the pads 210 . In FIG. 2 , the first pad 312 and the second pad 322 are shown as being disposed on opposite sides of the support membrane 200, but the present invention is not limited thereto.

A first insulating layer 400 may be disposed on the support film 200. The first insulating layer 400 may cover the first thermoelectric element 310, the second thermoelectric element 320, and the first connection electrode 330. At this time, a part of the first thermoelectric element 310 or a part of the second thermoelectric element 320 may be exposed to the outside of the first insulating layer 400 as shown in FIG. 2.

An infrared filter 500 may be provided on the first insulating layer 400. The infrared filter 500 can selectively pass infrared rays among the light incident on the infrared sensor. The infrared filter 500 may be a filter using a surface plasmon resonance (SPR) phenomenon or a metamaterial resonance phenomenon. The infrared filter 500 may include metal patterns 510 and a second insulating layer 520. Figure 4 is a plan view for explaining an infrared filter.

Referring to FIGS. 1, 3, and 4, metal patterns 510 may be disposed on the first insulating layer 400. The metal patterns 510 may be arranged on the top surface of the first insulating layer 400 at regular intervals from each other. At this time, the interval at which the metal patterns 510 are periodically arranged may be smaller than the wavelength of the electromagnetic wave in the infrared band. By arranging the metal patterns 510, the infrared filter 500 may have a negative refractive index for electromagnetic waves in the infrared band. Accordingly, the infrared filter 500 can selectively pass infrared rays among the light incident on the infrared sensor. The infrared filter 500 may have a large optical absorption cross-sectional area, and a high infrared absorption rate can be obtained even when a small-sized infrared filter 500 is used.

A second insulating layer 520 may be disposed on the metal patterns 510 . The second insulating layer 520 may cover the metal patterns 510 . The second insulating layer 520 may protect the metal patterns 510 and insulate the metal patterns 510.

According to embodiments of the present invention, an infrared filter 500 may be provided on the first thermoelectric element 310 and the second thermoelectric element 320 that detect infrared rays. Accordingly, infrared rays incident from the outside can be transmitted to the first and second thermoelectric elements 310 and 320 with high efficiency, and the sensitivity of the infrared sensor can be improved.

In addition, the support film 200 on which the first thermoelectric element 310 and the second thermoelectric element 320 are disposed is spaced apart from the substrate 100, so that the first and second thermoelectric elements 310 and 320 and the substrate ( 100) An empty space (AS) may be provided between. Accordingly, heat incident to the infrared sensor can be prevented from leaking through the substrate 100, and the sensitivity of the infrared sensor can be improved.

In addition, the structural stability of the infrared sensor can be improved by supporting the center of the support film 200, which is spaced from the substrate 100, through the second support part 220.

Figure 5 is a plan view for explaining an infrared sensor according to embodiments of the present invention. Figures 6 and 7 are cross-sectional views for explaining an infrared sensor according to embodiments of the present invention, and correspond to a cross-section taken along line B-B' in Figure 5. In the following embodiments, the same reference numerals are used for components described in the embodiments of FIGS. 1 to 4, and for convenience of explanation, descriptions thereof are omitted or briefly explained. That is, the description will focus on the differences between the embodiments of FIGS. 1 to 4 and the embodiments below.

Referring to FIGS. 5 and 6 , a support film 200 may be disposed on the substrate insulating layer 110 . The support film 200 may be spaced upward from the substrate insulating layer 110 . An empty space AS may be defined between the substrate insulating layer 110 and the support film 200. From a plan view, the support membrane 200 may have a square shape.

The first thermoelectric element 310 and the second thermoelectric element 320 may be provided in plural numbers. One side of the first thermoelectric elements 310 may be disposed to face the center of the support membrane 200, and the other side may be disposed to face the outer portion of the support membrane 200. One side of the second thermoelectric elements 320 may be disposed to face the center of the support membrane 200, and the other side may be disposed to face the outer portion of the support membrane 200. The first thermoelectric elements 310 and the second thermoelectric elements 320 may be alternately connected to each other in series. At this time, the hot junction of the thermocouple formed by one of the first thermoelectric elements 310 and one of the second thermoelectric elements 320 faces the center of the support film 200, and the thermocouple The cold junction may be directed to the outer portion of the support film 200. When a plurality of thermocouples of the first and second thermoelectric elements 310 and 320 are provided, the total output voltage generated from the thermocouples in response to external infrared rays is greater than when a single thermoelectric pair is provided. You can.

The first thermoelectric elements 310 and the second thermoelectric elements 320 may be connected in series through a plurality of first connection electrodes 330 and second connection electrodes 340. As an example, the hot junction of the thermocouple formed by one of the first thermoelectric elements 310 and one of the second thermoelectric elements 320 is connected through the first connection electrodes 330, and the cold junction of the thermocouple is may be connected through second connection electrodes 340. Accordingly, the first connection electrodes 330 may be disposed on the center of the support membrane 200, and the second connection electrodes 340 may be disposed on the outer portion of the support membrane 200.

In FIG. 6, the first connection electrodes 330 are shown to be located at the same level as the first thermoelectric elements 310 and the second thermoelectric elements 320, but the first connection electrodes 330 are shown in FIG. As shown in 7, it may be disposed on the first thermoelectric elements 310 and the second thermoelectric elements 320 to electrically connect the first thermoelectric elements 310 and the second thermoelectric elements 320. there is.

The first pad 312 and the second pad 322 may be disposed on opposite sides of the support membrane 200 . In Figure 5, the electrical connection of the first thermoelectric elements 310 and the second thermoelectric elements 320 is on both sides of the support film 200 around the axis connecting the first pad 312 and the second pad 322. Although it is shown that two series circuits are formed in parallel, the present invention is not limited to this, and the electrical connection of the first thermoelectric elements 310 and the second thermoelectric elements 320 has only one series circuit. You can.

Figure 8 is a plan view for explaining an infrared sensor according to embodiments of the present invention. FIG. 9 is a cross-sectional view for explaining an infrared sensor according to embodiments of the present invention, and corresponds to a cross-section taken along line C-C' of FIG. 8.

Referring to FIGS. 8 and 9 , a plurality of first thermoelectric elements 310 and 320 may be provided. The first thermoelectric elements 310 and the second thermoelectric elements 320 may be alternately connected to each other in series. The hot junction of the thermocouples formed by the first thermoelectric elements 310 and the second thermoelectric elements 320 points toward the center of the support film 200, and the cold junction of the thermocouple may be directed to the outer portion of the support membrane 200.

The first thermoelectric elements 310 and the second thermoelectric elements 320 may be connected in series through a plurality of first connection electrodes 330 and second connection electrodes 340. As an example, the hot junction of the thermocouple formed by one of the first thermoelectric elements 310 and one of the second thermoelectric elements 320 is connected through the first connection electrodes 330, and the cold junction of the thermocouple is may be connected through second connection electrodes 340.

The first pad 312 and the second pad 322 may be disposed together on one side of the support membrane 200 .

10 to 14 are cross-sectional views for explaining a method of manufacturing an infrared sensor according to embodiments of the present invention. Hereinafter, a method of manufacturing an infrared sensor will be described based on the infrared sensor of FIGS. 5 and 6.

Referring to FIGS. 5 and 10 , a substrate insulating layer 110 may be formed on the substrate 100 . The substrate 100 may include silicon (Si) or a compound semiconductor. The substrate insulating layer 110 may be formed by depositing silicon oxide, silicon nitride, or an organic material on the upper surface of the substrate 100.

Referring to FIGS. 5 and 11 , a sacrificial layer 600 may be formed on the substrate insulating layer 110 . For example, the sacrificial layer 600 may be formed by depositing an oxide or organic material and patterning the deposited oxide layer or organic material layer. The sacrificial layer 600 may have a through hole 610 penetrating its interior to expose the top surface of the substrate insulating layer 110.

A support film 200 may be formed on the sacrificial layer 600. For example, an insulating material may be deposited on the substrate insulating layer 110 and the sacrificial layer 600, and the deposited insulating material may be patterned. The support film 200 may be spaced apart from the substrate insulating layer 110 by the sacrificial layer 600 .

During the forming process of the support film 200, the first support parts 210 and the second support parts 220 may be formed together. The first supports 210 and the second supports 220 may be formed between the substrate insulating layer 110 and the support film 200. The first supports 210 may be formed on the sidewall of the sacrificial layer 600 . The second support part 220 may be formed in the through hole 610 of the sacrificial layer 600. When depositing the insulating material, the insulating material may cover the top and side surfaces of the sacrificial layer 600 and fill the through hole 610 of the sacrificial layer 600. During the patterning process of the insulating material, the insulating material on the top surface of the substrate insulating layer 110 and the side of the sacrificial layer 600 is etched together to form first supports 210, and the sacrificial layer 600 penetrates. The insulating material within the hole 610 may form the second support 220 . The first supports 210 and the second supports 220 may be formed substantially integrally with the support membrane 200 .

Referring to FIGS. 5 and 12 , first thermoelectric elements 310 and second thermoelectric elements 320 may be formed on the sacrificial layer 600 . For example, a semiconductor material may be deposited on the support film 200, and the deposited semiconductor material may be patterned. Thereafter, the first thermoelectric elements 310 and the second thermoelectric elements 320 may be formed by doping n-type impurities or p-type impurities on the patterned semiconductor material.

During the formation process of the first and second thermoelectric elements 310 and 320, the first pad 312 and the second pad 322 may be formed together. The first pad 312 and the second pad 322 may be formed on one of the first supports 210, respectively. When depositing the semiconductor material, the semiconductor material may cover the first supports 210 . During the patterning process of the semiconductor material, the semiconductor material on the first supports 210 may be etched together to form the first pad 312 and the second pad 322. The first pad 312 may be formed substantially integrally with any one of the first thermoelectric elements 310, and the second pad 322 may be formed substantially integrally with any one of the second thermoelectric elements 320. It can be.

Referring to FIGS. 5 and 13 , first connection electrodes 330 and second connection electrodes 340 may be formed on the support membrane 200 . For example, a conductive material may be deposited on the support film 200, and the deposited conductive material may be patterned. The conductive material may include a metal such as platinum (Pt), aluminum (Al), or gold (Au), or a conductive metal oxide.

A first insulating layer 400 may be formed on the support film 200. The first insulating layer 400 includes first thermoelectric elements 310, second thermoelectric elements 320, first connection electrodes 330, and second connection electrodes 340 on the support membrane 200. It can be formed by depositing an insulating material covering the. The first insulating layer 400 may be formed to cover thermal contact points of thermocouples formed by the first thermoelectric elements 310 and the second thermoelectric elements 320.

Referring to FIGS. 5 and 14 , an infrared filter 500 may be formed on the first insulating layer 400. In detail, after forming metal patterns 510 on the first insulating layer 400, an infrared filter 500 is formed by forming a second insulating layer 520 covering the metal patterns 510. You can. The metal patterns 510 may be formed by forming a conductive material on the first insulating layer 400 and then patterning the conductive material. The second insulating layer 520 may be formed to cover the metal patterns 510 .

Referring again to FIGS. 5 and 6 , the sacrificial layer 600 may be removed by an etching process. For example, the etching solution or etching gas may flow into one side of the sacrificial layer 600 and react with the sacrificial layer 600. The sacrificial layer 600 that reacted with the etching gas may be removed to the outside. By removing the sacrificial layer 600, an empty space AS may be formed between the substrate insulating layer 110 and the support film 200.

The infrared sensors of FIGS. 5 and 6 can be formed through the above process.

Above, embodiments of the present invention have been described with reference to the attached drawings, but those skilled in the art will understand that the present invention can be implemented in other specific forms without changing the technical idea or essential features. You will understand that it exists. Therefore, the embodiments described above should be understood in all respects as illustrative and not restrictive.

100: substrate 110: substrate insulating layer
200: support membrane 310: first thermoelectric element
320: second thermoelectric element 330: first connection electrode
340: second connection electrode 400: first insulating layer
500: Infrared filter 510: Metal pattern
520: second insulating layer 600: sacrificial layer

Claims (10)

Board;
a support film disposed on the substrate and spaced apart from the substrate;
A first thermoelectric element and a second thermoelectric element are spaced apart from each other on the support film, and the first and second thermoelectric elements include semiconductor materials of different conductivity types;
a connection electrode connecting one end of the first thermoelectric element and one end of the second thermoelectric element on the support membrane;
an insulating layer covering the first thermoelectric element, the second thermoelectric element, and the connection electrode on the support membrane; and
An infrared filter disposed between the insulating layer and located above the first and second thermoelectric elements,
The infrared filter includes metal patterns periodically formed at intervals smaller than the wavelength of an electromagnetic wave in the infrared band incident on the infrared filter,
The infrared filter is an infrared sensor that selectively passes electromagnetic waves in the infrared band. According to claim 1,
An infrared sensor further comprising a support part provided between the substrate and the support film to support the center of the support film. delete According to claim 1,
The first thermoelectric element and the second thermoelectric element are infrared sensors located above an empty space between the substrate and the support film. delete delete According to claim 1,
The first thermoelectric element and the second thermoelectric element are provided in plural,
The connection electrode includes first connection electrodes connecting the pair of the first thermoelectric element and the second thermoelectric element on the center of the support membrane, and a pair of the first thermoelectric element and the second thermoelectric element on the outer portion of the support membrane. Includes second connection electrodes connecting the elements,
The first thermoelectric elements and the second thermoelectric elements are alternately connected in series by the first connection electrodes and the second connection electrodes. forming a substrate insulating layer on the substrate;
forming a sacrificial layer on the substrate insulating layer;
Forming a support film on the sacrificial layer;
forming a first thermoelectric element and a second thermoelectric element on the support membrane;
forming a connection electrode connecting the first thermoelectric element and the second thermoelectric element on the support membrane;
forming a first insulating layer covering the first thermoelectric element, the second thermoelectric element, and the connection electrode on the support membrane;
forming an infrared filter by forming metal patterns on the first insulating layer and then forming a second insulating layer covering the metal patterns; and
Including removing the sacrificial layer,
The metal patterns are formed periodically at intervals smaller than the wavelength of the electromagnetic wave in the infrared band incident on the infrared filter,
The infrared filter is a method of manufacturing an infrared sensor that selectively passes electromagnetic waves in the infrared band. According to claim 8,
Forming the first thermoelectric element and the second thermoelectric element:
depositing a semiconductor material on the support film;
patterning the semiconductor material; and
Doping impurities on the patterned semiconductor material to form the first thermoelectric element and the second thermoelectric element,
A method of manufacturing an infrared sensor wherein the first thermoelectric element and the second thermoelectric element have different conductivity types. According to claim 8,
The first thermoelectric element and the second thermoelectric element are positioned above an empty space between the substrate insulating layer and the support film.

Images