Infrared Sensor Using Single Crystalline Silicon to Eliminate Flicker Noise
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Solution Overview
Problem
Conventional infrared sensors face issues with flicker noise, low resistance change rate, increased complexity and cost due to mechanical choppers, and image lag, which affect their performance in sensing infrared radiation.
Innovation Solution
A semiconductor device with a light receiving portion and a sensing portion that uses single crystalline silicon, a MEMS-based heat removal structure, and a sensing circuit to efficiently reset heat and minimize common mode current effects, eliminating the need for mechanical choppers and enhancing signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If VOx is used as the resistive detecting element, then the resistance change rate to temperature change is improved, but the flicker noise becomes excessively large
Solution Approach 1:
The patent changes the material parameter from conventional VOx to single crystalline silicon, which fundamentally alters the noise characteristics while maintaining the resistance change rate to temperature change property. Single crystalline silicon exhibits significantly lower flicker noise compared to VOx, thus resolving the contradiction between measurement precision and harmful noise generation.
2Measurement precision
If a mechanical chopper is provided to improve sensing performance, then the detection accuracy is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent extracts and eliminates the mechanical chopper component from the infrared sensing system. By using single crystalline silicon as the detecting element, the system achieves improved detection accuracy without requiring external mechanical chopping mechanisms, thus reducing device complexity and manufacturing cost while maintaining measurement precision.
Solution Approach 2:
The patent replaces the mechanical chopper system with an electrical/material-based solution using single crystalline silicon. This substitution eliminates moving parts and mechanical complexity while achieving the same or better detection accuracy through the material's inherent properties of low flicker noise and appropriate resistance change rate.
3Object-generated harmful factors
If titanium is used as the resistive detecting element, then the flicker noise is reduced, but the resistance change rate to temperature change becomes too small
Solution Approach 1:
The patent changes the material parameter from titanium to single crystalline silicon, which simultaneously optimizes both flicker noise levels and resistance change rate to temperature change. Single crystalline silicon provides a balanced performance with low flicker noise comparable to titanium but with a significantly higher resistance change rate, thus resolving the contradiction between noise reduction and measurement sensitivity.
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
The solution improves infrared radiation sensing performance by reducing noise, increasing resistance change rate, and eliminating image lag, resulting in enhanced sensitivity and operational speed without the complexity and cost of mechanical choppers.
Implementation Method 1
a light receiving portion (1) which converts energy of photons into heat
Implementation Method 2
a sensing portion (3) of which resistance varies according to heat converted by the light receiving portion
Implementation Method 3
a heat removing portion (5) for removing heat accumulated in the light receiving portion (1) and the sensing portion (3)
Implementation Method 4
an actuating voltage which applies electric potential between the sensing portion (3) and the heat removing portion (5) such that the light receiving portion (1) and the sensing portion (3) elastically deflect into the space to contact the heat removing portion (5)
Data Source
AI summary
A semiconductor device for sensing infrared radiation is provided. In an embodiment, the semiconductor device includes a sensor configuration which includes a light receiving portion for converting incident photons into heat and a sensing portion integrated with the light receiving portion and having a resistance varying according to the converted heat; and a sensing circuit which includes a common mode current providing portion and a current subtraction portion, wherein the common mode current providing portion outputs a common mode current related to a value of a current which is flowing in the sensing portion when there is no incident light and the current subtraction portion outputs subtraction currents for the common mode current and a sensing current related to a current output from the sensing portion.In another embodiment, the sensing configuration includes a heat removing portion which is disposed to form an empty space between the heat removing portion and the light receiving portion and the sensing portion, and removes accumulated heat from the light receiving portion and the sensing portion, and the sensing circuit includes an actuating voltage supplying portion which applies electric potential between the sensing portion and the heat removing portion to make the light receiving portion and the sensing portion elastically deflect into the empty space and consequently contact the heat removing portion to remove the heat.