Flash Cell Undercut Spacer for Leakage Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Flash memory cells experience circuit leakage due to the sharp tips of selective gates, which is not effectively addressed by existing technologies.
Innovation Solution
A flash cell forming process that involves forming a spacer with a bottom part removal to create an undercut, allowing a selective gate to extend and fill into this undercut, thereby rounding the selective gate and preventing leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a selective gate is formed with a sharp tip to improve gate control, then gate control is improved, but circuit leakage increases
Solution Approach 1:
The patent applies curvature by forming an undercut structure at the bottom of the spacer, which causes the selective gate to have a rounded tip instead of a sharp tip. This is achieved by removing the bottom part of the spacer to create an undercut, allowing the gate material to form a curved profile that extends into the undercut region. The rounded gate tip eliminates the sharp edge that causes leakage while maintaining adequate gate control.
2Object-generated harmful factors
If the selective gate tip is rounded to reduce circuit leakage, then circuit leakage is reduced, but gate control may deteriorate
Solution Approach 1:
The patent extends the selective gate into the undercut dimension, creating a three-dimensional gate structure that compensates for the reduced control effect at the rounded tip. The gate material fills the undercut space, providing additional control coverage in the vertical dimension while the rounded tip maintains low leakage. This dimensional extension ensures that gate control is maintained despite the curved profile.
Data Source
AI summary
A flash cell forming process includes the following steps. A first gate is formed on a substrate. A first spacer is formed at a side of the first gate, where the first spacer includes a bottom part and a top part. The bottom part is removed, thereby an undercut being formed. A first selective gate is formed beside the first spacer and fills into the undercut. The present invention also provides a flash cell formed by said flash cell forming process. The flash cell includes a first gate, a first spacer and a first selective gate. The first gate is disposed on a substrate. The first spacer is disposed at a side of the first gate, where the first spacer has an undercut at a bottom part, and therefore exposes the substrate. The first selective gate is disposed beside the first spacer and extends into the undercut.