Bio-sensor Nanocavity Structure for CMOS Integration and Corrosion Resistance
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Solution Overview
Problem
Current bio-sensors lack the combination of high accuracy, sensitivity, acid and alkali resistance, and anti-corrosion properties, while also requiring integration with CMOS image sensors for cost reduction and power efficiency.
Innovation Solution
An integrated bio-sensor with a nanocavity structure is developed, comprising a substrate, light-sensing region, dielectric layers, trenched recess structure, light filter layer, and passivation layers, which includes a fabrication method involving deposition and etching processes to form a nanocavity capable of filtering specific wavelengths and resisting corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional bio-sensor structures are used, then fabrication simplicity is maintained, but acid and alkali resistance and anti-corrosion properties are insufficient
Solution Approach 1:
The patent employs a composite structure consisting of multiple dielectric layers (first dielectric layer, second dielectric layer), a diffusion barrier layer, and a passivation layer. Each layer is made of different materials with specific properties that collectively provide acid and alkali resistance while maintaining fabrication compatibility. The diffusion barrier layer specifically prevents ion diffusion, while the passivation layer provides chemical resistance, creating a composite protective system.
2Measurement precision
If bio-sensor performance is improved for high accuracy and sensitivity, then detection capability is enhanced, but integration with CMOS image sensors becomes more difficult
Solution Approach 1:
The patent designs a multi-functional structure where the same layer stack serves multiple purposes: the dielectric layers provide both structural support and chemical protection, the diffusion barrier layer prevents ion migration while maintaining electrical isolation, and the passivation layer provides both mechanical protection and chemical resistance. This universal design enables the bio-sensor to achieve high detection accuracy while remaining compatible with standard CMOS fabrication processes.
Solution Approach 2:
The patent optimizes various parameters including the thickness of each layer, the refractive index of dielectric materials, and the nanocavity dimensions to achieve both high detection sensitivity and compatibility with CMOS processes. By carefully controlling these parameters, the design balances performance requirements with manufacturing constraints.
3Measurement precision
If nanocavity volume is precisely controlled for high sensitivity, then detection sensitivity is improved, but fabrication precision requirements increase
Solution Approach 1:
The patent forms the nanocavity structure through preliminary patterning and etching steps that define the cavity geometry before subsequent layer deposition. The cavity shape and dimensions are established early in the fabrication process using photolithography and etching techniques, allowing precise control of the nanocavity volume while using standard semiconductor manufacturing processes.
4Measurement precision
If light filtering capability is enhanced for noise reduction, then signal-to-noise ratio is improved, but light transmission to sensing region may be reduced
Solution Approach 1:
The patent implements wavelength-selective filtering where the light filter layer is designed to block only specific noise wavelengths while transmitting the signal wavelengths needed for detection. This local quality approach allows the filter to discriminate between harmful noise light and useful signal light, improving the signal-to-noise ratio without significantly reducing overall light transmission to the sensing region.
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 bio-sensor achieves fast, high-accuracy, and high-sensitivity biochemical reactions with acid and alkali resistance, enabling integration with CMOS image sensors for cost reduction and power efficiency, while maintaining precise control over nanocavity volume.
Implementation Method 1
The light filter layer is configured to block light within a specific wavelength range and filter out noise light, and light within another specific wavelength range may pass through the light filter layer and irradiate the light-sensing region
Data Source
AI summary
A bio-sensor includes a substrate having a light-sensing region thereon. A first dielectric layer, a diffusion barrier layer, and a second dielectric layer are disposed on the substrate. A trenched recess structure is formed in the second dielectric layer, which is filled with a light filter layer that is capped with a cap layer. A first passivation layer and a nanocavity construction layer are disposed on the cap layer. A nanocavity is formed in the nanocavity construction layer. The sidewall and bottom surface of the nanocavity is lined with a second passivation layer.