Floating Gate Shielding for OTP Memory Ion Blocking
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
One-time programmable (OTP) memory cells face device mismatch issues due to performance variation during manufacturing, primarily caused by dangling bonds on semiconductor substrates, which are exacerbated by the hydrogen alloy process that neutralizes charge stored in the floating gate, reducing reliability and data retention.
Innovation Solution
Implementing a floating gate shielding mechanism where conductive features are stacked over the OTP memory cell's interconnect structure, with at least one feature directly overlaying the floating gate to prevent ion diffusion, such as hydrogen ions, thereby maintaining charge and enhancing data retention and reliability without additional semiconductor manufacturing processes or costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the hydrogen alloy process is used to terminate dangling bonds on semiconductor substrates, then device mismatch is reduced, but the floating gate charge is neutralized, reducing reliability and data retention
Solution Approach 1:
A shield structure is introduced as an intermediary element positioned between the hydrogen alloy process zone and the floating gate. This shield selectively blocks hydrogen ions from reaching the floating gate while allowing the hydrogen alloy process to proceed on the semiconductor substrate, thus protecting the stored charge from neutralization while still enabling dangling bond termination
Solution Approach 2:
The shield structure is positioned locally over the floating gate region, creating a localized protection zone. This allows the hydrogen alloy process to be applied globally to the semiconductor substrate for terminating dangling bonds, while simultaneously providing localized protection to the floating gate area where charge storage occurs, thus resolving the contradiction between global manufacturing precision improvement and local reliability preservation
2Ease of manufacture
If conventional OTP memory cell structure is used, then manufacturing is simple, but device mismatch and performance variation occur due to dangling bonds
Solution Approach 1:
The shield structure is merged with the existing interconnect structure of the OTP memory cell. By integrating the shield into the interconnect layers and utilizing existing manufacturing steps, the solution adds minimal complexity to the manufacturing process while effectively addressing device mismatch caused by dangling bonds
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 floating gate shielding effectively prevents ion diffusion, ensuring good data retention and high reliability of OTP memory cells while reducing device mismatch, thus improving the overall performance and consistency of OTP memory cells.
Implementation Method 1
the hydrogen alloy process also introduces hydrogen ions to the floating gate
Implementation Method 2
At least one of the conductive features directly overlies the floating gate and shields the floating gate from ions
Data Source
AI summary
A one-time programmable (OTP) memory cell with floating gate shielding is provided. A pair of transistors is arranged on a semiconductor substrate and electrically coupled in series, where the transistors comprise a floating gate. An interconnect structure overlies the pair of transistors. A shield is arranged in the interconnect structure, directly over the floating gate. The shield is configured to block ions in the interconnect structure from moving to the floating gate. A method for manufacturing an OTP memory cell with floating gate shielding is also provided.