Terahertz Sensor Absorber Orientation for Faster Thermal Response

Solution Overview

Problem

In sensors with a thermal separation structure, poor heat transfer characteristics of the light absorbing film lead to slow response times due to the absorption of terahertz waves, affecting sensitivity and resolution.

Innovation Solution

The sensor design includes a substrate, a diaphragm with a light absorbing film having a fibrous or sheet-like material that absorbs terahertz waves, and a temperature sensing element. The light absorbing film is oriented such that the mean angle of its material direction relative to the substrate is 45° or less, enhancing thermal conductivity parallel to the substrate.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the light absorbing film has poor heat transfer characteristics, then the sensitivity is improved, but the response speed decreases

Engineering Contradiction:

ImprovesensitivityVSAvoidresponse speed

Core Design Contradiction:

Measurement precisionVSSpeed

Solution Approach 1:

The patent applies local quality by creating anisotropic thermal conductivity within the light absorbing film through oriented fibrous material. The film has high thermal conductivity in the planar direction (parallel to substrate) to rapidly transfer heat laterally to the temperature sensing element, while maintaining low thermal conductivity in the thickness direction to preserve thermal separation and sensitivity. This directional differentiation of thermal properties resolves the contradiction between sensitivity and response speed.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent uses composite materials by combining fibrous material with specific orientation characteristics into the light absorbing film. The fibrous structure provides preferential thermal conduction paths in the planar direction, creating a composite material with anisotropic thermal properties. This composite approach enables simultaneous achievement of fast lateral heat transfer (high response speed) and effective thermal separation (high sensitivity).

Inventive Principle:

Principle #40Composite materials

2Measurement precision

If the pixel size is increased to detect 1 THz waves, then the sensitivity is improved, but the heat transfer characteristics worsen

Engineering Contradiction:

ImprovesensitivityVSAvoidheat transfer characteristics

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent applies local quality by creating anisotropic thermal conductivity within the light absorbing film through oriented fibrous material. The film has high thermal conductivity in the planar direction (parallel to substrate) to rapidly transfer heat laterally to the temperature sensing element, while maintaining low thermal conductivity in the thickness direction to preserve thermal separation and sensitivity. This directional differentiation of thermal properties resolves the contradiction between sensitivity and response speed.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent uses composite materials by combining fibrous material with specific orientation characteristics into the light absorbing film. The fibrous structure provides preferential thermal conduction paths in the planar direction, creating a composite material with anisotropic thermal properties. This composite approach enables simultaneous achievement of fast lateral heat transfer (high response speed) and effective thermal separation (high sensitivity).

Inventive Principle:

Principle #40Composite materials

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This configuration improves the sensor's sensitivity and response speed by facilitating faster heat transfer from the light absorbing film to the temperature sensing element, while maintaining high absorptivity for terahertz waves.

Implementation Method 1

a light absorbing film that absorbs an electromagnetic wave

Methodology Applied

Scientific EffectAbsorption of electromagnetic radiation: Absorption (EM radiation)

Implementation Method 2

thermal conductivity in a direction parallel to the substrate is higher than thermal conductivity in a direction perpendicular to the substrate

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS20250027818A1Sensor, imaging device and electronic device

Publication Date: 2025.01.23 SONY SEMICON SOLUTIONS CORP

AI summary

A sensor according to an embodiment of the present disclosure includes a substrate, a diaphragm including a light absorbing film disposed with a cavity interposed between the light absorbing film and the substrate, a beam portion that supports the diaphragm on the substrate, and a temperature sensing element that detects a temperature change of the light absorbing film. The light absorbing film contains a fibrous material or a sheet-like material that absorbs terahertz waves or infrared rays. The mean value of angles formed by a direction of the fibrous material or a planar direction of a sheet and a direction parallel to the substrate is 45° or less at least in a part of a region of the light absorbing film.