US-12622076-B2 - Infrared sensor and method of manufacturing infrared sensor

US12622076B2US 12622076 B2US12622076 B2US 12622076B2US-12622076-B2

Abstract

An infrared sensor includes a first semiconductor substrate, a second semiconductor substrate, a sealing frame, and a first connection. The first semiconductor substrate includes a first main surface and an infrared detection element. The second semiconductor substrate includes a second main surface and a signal processing circuit. The sealing frame surrounds an internal space with the first main surface, the infrared detection element, and the second main surface. The first connection electrically connects the infrared detection element and the signal processing circuit. The internal space is hermetically sealed by the first main surface, the infrared detection element, the second main surface, and the sealing frame. Each of the sealing frame and the first connection is sandwiched between the first main surface and the second main surface.

Inventors

Daisuke Fujisawa
Takashi Takenaga

Assignees

MITSUBISHI ELECTRIC CORPORATION

Dates

Publication Date: 20260505
Application Date: 20200703

Claims (17)

1 . An infrared sensor comprising: a first semiconductor substrate including a first main surface and an infrared detection element disposed at the first main surface; a second semiconductor substrate including a second main surface facing the first main surface, and a signal processing circuit to process a signal of the infrared detection element; a sealing frame connected to the first semiconductor substrate and the second semiconductor substrate, surrounding the infrared detection element disposed at the first main surface, and forming an internal space that is hermetically sealed by the first main surface, the infrared detection element, and the second main surface; and a first connection disposed on the first main surface, located outside the sealing frame, and electrically connecting the infrared detection element and the signal processing circuit, wherein the internal space is hermetically sealed by the first main surface, the infrared detection element, the second main surface, and the sealing frame, and each of the sealing frame and the first connection is sandwiched between the first main surface and the second main surface, and the signal processing circuit is disposed in a region outside the internal space.
2 . The infrared sensor according to claim 1 , further comprising an antireflective film disposed on a side opposite to the second semiconductor substrate with respect to the first main surface, wherein the antireflective film prevents reflection of infrared radiation.
3 . The infrared sensor according to claim 1 , wherein the first semiconductor substrate includes a first substrate portion and a first infrared transmitting portion to transmit infrared radiation more than the first substrate portion, and the first infrared transmitting portion faces the infrared detection element.
4 . The infrared sensor according to claim 1 , further comprising an antireflective film disposed on a side opposite to the first semiconductor substrate with respect to the second main surface, wherein the antireflective film prevents reflection of infrared radiation.
5 . The infrared sensor according to claim 1 , wherein the second semiconductor substrate includes a second substrate portion and a second infrared transmitting portion to transmit infrared radiation more than the second substrate portion, and the second infrared transmitting portion faces the infrared detection element.
6 . The infrared sensor according to claim 1 , wherein the second main surface includes a second main surface portion and a depressed portion, and the depressed portion is provided at a position facing the infrared detection element to be depressed from the second main surface portion.
7 . The infrared sensor according to claim 1 , further comprising a second connection, wherein the second connection is sandwiched between the first main surface and the second main surface.
8 . The infrared sensor according to claim 7 , wherein the second connection has an outer diameter different from an outer diameter of the first connection.
9 . The infrared sensor according to claim 7 , wherein the second connection has a higher melting point than the first connection and the sealing frame.
10 . The infrared sensor according to claim 1 , wherein a material of each of the first connection and the sealing frame has electrical conductivity.
11 . The infrared sensor according to claim 1 , wherein a material of the first connection is same as a material of the sealing frame.
12 . The infrared sensor according to claim 1 , wherein the internal space is sealed in a vacuum state.
13 . A method of manufacturing an infrared sensor, comprising the steps of: preparing a first semiconductor substrate including a first main surface and an infrared detection element disposed at the first main surface, a second semiconductor substrate including a second main surface and a signal processing circuit to process a signal of the infrared detection element, a sealing frame, and a first connection; and sandwiching each of the scaling frame and the first connection between the first main surface, the infrared detection element, and the second main surface to form an internal space that is hermetically sealed by the first main surface, the infrared detection element, the second main surface, and the sealing frame, surround, by the sealing frame, the infrared detection element disposed at the first main surface, and dispose the signal processing circuit in a region outside the internal space, and electrically connecting the infrared detection element and the signal processing circuit by the first connection outside the sealing frame.
14 . The method of manufacturing an infrared sensor according to claim 13 , wherein the internal space is hermetically sealed by the first main surface, the infrared detection element, the second main surface, and the sealing frame in a vacuum atmosphere.
15 . The method of manufacturing an infrared sensor according to claim 13 , wherein a second connection is further prepared, and the second connection is sandwiched together with the sealing frame and the first connection between the first main surface and the second main surface.
16 . An infrared sensor comprising: a first semiconductor substrate including a first main surface and an infrared detection element disposed at the first main surface; a second semiconductor substrate including a second main surface facing the first main surface, and a signal processing circuit to process a signal of the infrared detection element; a sealing frame connected to the first semiconductor substrate and the second semiconductor substrate and surrounding an internal space with the first main surface, the infrared detection element, and the second main surface; a first connection electrically connecting the infrared detection element and the signal processing circuit, wherein the internal space is hermetically sealed by the first main surface, the infrared detection element, the second main surface, and the sealing frame, and each of the sealing frame and the first connection is sandwiched between the first main surface and the second main surface; and a second connection, wherein the second connection is sandwiched between the first main surface and the second main surface, and the second connection has a higher melting point than the first connection and the sealing frame.
17 . The infrared sensor according to claim 16 , wherein the second connection is sandwiched between the first main surface and the second main surface.

Description

CROSS-REFERENCE TO RELATED APPLICATION The present application is based on PCT filing PCT/JP2020/026226, filed Jul. 3, 2020, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD The present disclosure relates to an infrared sensor and a method of manufacturing an infrared sensor. BACKGROUND ART Infrared sensors are classified into the quantum type (cooling type) and the thermal type (non-cooling type). A thermal infrared sensor converts infrared radiation absorbed by an infrared absorber into heat. The thermal infrared sensor converts temperature change caused by the converted heat into an electrical signal. The temperature change by infrared radiation occurs in an infrared detector of the thermal infrared sensor. An insulation structure with which the infrared detector is thermally isolated from the substrate of the thermal infrared sensor increases the temperature change of the infrared detector caused by the infrared detector absorbing the incident infrared radiation. The infrared detector may be held in an internal space in a vacuum in the insulation structure. This suppresses reduction in thermal resistance of the insulation structure due to heat transfer through gas and gas convection in the internal space, thereby further enhancing thermal insulation. An infrared sensor having an infrared sensor substrate and a signal processing circuit substrate facing each other is also known. An insulation structure is provided between the infrared sensor substrate and the signal processing circuit substrate. The internal space of the insulation structure is hermetically sealed to be thermally insulated. The infrared sensor substrate has a pixel array formed with a plurality of pixels including infrared detection elements. The signal processing circuit substrate has a signal processing circuit for processing an output signal from each infrared detection element. The signal processing circuit is, for example, an analog/digital conversion circuit. An example of the infrared sensor having the structure as described above is an optical device (infrared sensor) described in WO20061095834 (PTL 1). In the optical device described in the publication above, a photoelectric conversion portion (infrared detection element) faces an aperture (internal space) hermetically sealed. The aperture is hermetically sealed by a first main surface of a substrate (first semiconductor substrate) having the photoelectric conversion portion, the photoelectric conversion portion, a second main surface of a signal processing circuit portion (second semiconductor substrate), a sealing material, and interconnection wiring (first connection). CITATION LIST Patent Literature PTL 1 WO2006/095834 SUMMARY OF INVENTION Technical Problem In the optical device described in the publication above, after the substrate and the signal processing circuit portion are electrically connected by the interconnection wiring, the substrate, the signal processing circuit portion, and the connection wiring are hermetically sealed by the sealing material. The aperture is formed by removing the sealing material. Thus, in the optical device described in the publication above, the scaling of the aperture and the electrical connection between the substrate and the signal processing circuit portion are performed separately. This increases the manufacturing cost of the infrared sensor. The present disclosure is made in view of the problem above and an object of the present disclosure is to provide an infrared sensor and a method of manufacturing an infrared sensor that can suppress increase of the manufacturing cost. Solution to Problem An infrared sensor according to the present disclosure includes a first semiconductor substrate, a second semiconductor substrate, a sealing frame, and a first connection. The first semiconductor substrate includes a first main surface and an infrared detection element. The infrared detection element is arranged at the first main surface. The second semiconductor substrate includes a second main surface and a signal processing circuit. The second main surface faces the first main surface. The signal processing circuit processes a signal of the infrared detection element. The sealing frame is connected to the first semiconductor substrate and the second semiconductor substrate. The sealing frame surrounds an internal space with the first main surface, the infrared detection element, and the second main surface. The first connection electrically connects the infrared detection element and the signal processing circuit. The internal space is hermetically sealed by the first main surface, the infrared detection element, the second main surface, and the sealing frame. Each of the sealing frame and the first connection is sandwiched between the first main surface and the second main surface. Advantageous Effects of Invention In the infrared sensor according to the present disclosure, increase of the manufacturing cost