Native Oxide Removal and Dielectric Control for Biosensor Substrates
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Solution Overview
Problem
Current methods for forming substrates for biological applications, such as pH sensing in DNA sequencing, face challenges with poor signal-to-noise ratios due to native oxide layers and uncontrollable active sites, which affect substrate performance and throughput.
Innovation Solution
A method involving the removal of native oxide layers using ligands in vapor phase followed by thermal desorption, and the deposition of dielectric layers with controlled active sites using precursors and water pulses in a process chamber, to enhance substrate performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wet etch chemistry or radical-based plasma cleaning is used to remove native oxide layer, then the native oxide layer is removed, but the other layers of the substrate are damaged creating inconsistencies and impurities
Solution Approach 1:
The patent uses a fluorocarbon-based plasma as an intermediary medium to selectively remove native oxide layers. The fluorocarbon plasma reacts specifically with titanium oxide to form volatile fluorinated oxide species that can be removed, while the titanium underlying layer remains intact. This intermediary chemical reaction enables selective oxide removal without the damaging effects of wet etching or conventional plasma cleaning on other substrate layers.
Solution Approach 2:
The patent employs controlled plasma parameters including fluorocarbon gas flow rate, plasma power, and processing temperature to achieve selective oxide removal. By optimizing these parameters, the process selectively targets the native oxide layer for removal while preserving the integrity of the titanium substrate and other sensitive layers. The plasma chemistry and physical conditions are tuned to create a window of selectivity that removes oxide but spares the underlying metal.
2Ease of manufacture
If conventional dielectric layer deposition is used, then the dielectric layer is formed, but the number of active sites cannot be controlled
Solution Approach 1:
The patent introduces dynamic control over dielectric layer properties by adjusting deposition parameters such as precursor flow rates, plasma power, and processing temperature during atomic layer deposition. This dynamic parameter control enables tuning of the dielectric layer composition and thickness, which directly influences the number of active sites. The process transitions from static, fixed-property deposition to a dynamically adjustable process that can optimize active site density for specific sensing applications.
Solution Approach 2:
The patent implements in-situ monitoring and feedback control during dielectric layer deposition to maintain precise control over active site formation. By monitoring deposition rate, layer uniformity, and surface properties in real-time, the process can adjust parameters to achieve the desired active site density. This feedback mechanism ensures consistent reproduction of the optimal dielectric layer properties across different substrates and production batches.
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 approach improves the signal-to-noise ratio and controls the number of active sites, leading to better sensing capabilities and uniformity in substrates for applications like DNA sequencing.
Implementation Method 1
removing a native oxide layer from a surface of the substrate by exposing the substrate to one or more ligands in vapor phase to volatize the native oxide layer
Implementation Method 2
thermally desorbing or otherwise etching the volatized native oxide layer
Implementation Method 3
depositing a dielectric layer selected to provide a controlled number of active sites on the surface of the substrate
Data Source
AI summary
Methods of removing native oxide layers and depositing dielectric layers having a controlled number of active sites on MEMS devices for biological applications are disclosed. In one aspect, a method includes removing a native oxide layer from a surface of the substrate by exposing the substrate to one or more ligands in vapor phase to volatize the native oxide layer and then thermally desorbing or otherwise etching the volatized native oxide layer. In another aspect, a method includes depositing a dielectric layer selected to provide a controlled number of active sites on the surface of the substrate. In yet another aspect, a method includes both removing a native oxide layer from a surface of the substrate by exposing the substrate to one or more ligands and depositing a dielectric layer selected to provide a controlled number of active sites on the surface of the substrate.