BioFET Protective Layer for Corrosion Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The fabrication and operation of biological field-effect transistors (BioFETs) face challenges due to compatibility issues between semiconductor fabrication processes and biological applications, sensitivity, and resolution limitations, particularly in maintaining the integrity of the top metal plate from corrosion and ensuring proper alignment of microwells to prevent misalignment-induced defects.
Innovation Solution
A method and structure for forming BioFETs with a protective layer over and surrounding the top metal stack, including a sensing layer on the microwell sidewalls to increase surface area and prevent corrosion, while maintaining proper alignment through a top metal stack design that includes an underlayer, top metal, and a protective layer, ensuring separation from analytes and reducing manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a top metal plate is used in BioFET fabrication, then electrical connectivity is improved, but the metal plate is susceptible to corrosion from analytes
Solution Approach 1:
A protective layer is introduced as an intermediary between the top metal plate and the analyte. This protective layer prevents direct contact between the metal and corrosive biological samples while maintaining electrical connectivity through the metal stack, thereby resolving the contradiction between electrical performance and corrosion resistance.
Solution Approach 2:
A thin film protective layer is deposited over the top metal plate to provide corrosion protection. This thin film approach maintains the electrical properties of the metal stack while providing a barrier against analyte-induced corrosion, balancing connectivity and protection.
2Manufacturing precision
If microwell alignment is made more stringent to prevent misalignment defects, then manufacturing precision is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The top metal stack structure is designed with dimensions and tolerances that provide a margin of error for microwell alignment. By pre-designing the alignment tolerance buffer into the metal stack geometry, the system accommodates manufacturing variations without requiring extremely tight alignment control, thus reducing device complexity while maintaining precision.
3Measurement precision
If the top metal plate area is increased to improve signal intensity, then sensing performance is improved, but the area available for other components is reduced
Solution Approach 1:
The top metal stack is configured with optimized local dimensions - the metal stack area is increased to enhance signal intensity at the sensing location, while the overall chip layout is optimized to accommodate this local increase without proportionally increasing total chip area. This allows targeted improvement of signal strength in the sensing region while maintaining efficient use of overall chip real estate.
Data Source
AI summary
The present disclosure provides a biological field effect transistor (BioFET) and a method of fabricating a BioFET device. The method includes forming a BioFET using one or more process steps compatible with or typical to a complementary metal-oxide-semiconductor (CMOS) process. The BioFET includes a microwells having a sensing layer, a top metal stack under the sensing layer, and a multi-layer interconnect (MLI) under the top metal stack. The top metal stack includes a top metal and a protective layer over and peripherally surrounding the top metal.