IMS Memory Cell Encoding for 3D Storage Density
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Solution Overview
Problem
In in-memory search (IMS) systems, large bias voltage differences between adjacent word lines induce transverse electric field effects, leading to hot carrier injection (HCl) and threshold voltage shifts, which degrade storage data and increase read failure, especially in 3D memory devices with higher storage density.
Innovation Solution
The proposed solution involves encoding search data and storage data using a two-step IMS encoding process. First, a dummy bit is added to the data string, and the data string is grouped into bit groups, which are then encoded to generate IMS encoded data. This encoded data is further processed to generate search voltages and threshold voltages, reducing the high voltage differences between word lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high bias voltage difference is applied between adjacent word lines for IMS operation, then search speed and parallelism are improved, but transverse electric field effects are induced causing hot carrier injection and threshold voltage shifts
Solution Approach 1:
The patent segments the voltage application by introducing intermediate voltage levels between the high and low word line voltages. This segmentation of the voltage range reduces the transverse electric field strength while maintaining the IMS search functionality, thereby preventing hot carrier injection and threshold voltage shifts.
Solution Approach 2:
The patent changes the voltage parameters by applying multiple intermediate voltage levels instead of a single high bias voltage difference. This parameter modification allows the system to maintain search capability while reducing the electric field intensity that causes harmful effects.
2Quantity of substance
If 3D memory devices have more memory layers or higher storage density, then storage capacity is improved, but threshold voltage shifts and read failure rates worsen due to cumulative transverse electric field effects
Solution Approach 1:
The patent applies segmentation by dividing the voltage difference across multiple intermediate levels in 3D memory structures. This approach reduces the cumulative transverse electric field effects across multiple memory layers, preventing threshold voltage shifts and read failures while maintaining high storage density.
Solution Approach 2:
The patent addresses the vertical stacking dimension in 3D memory by introducing intermediate voltage steps along the vertical word line structure. This dimensional approach to voltage distribution reduces the electric field intensity in each layer, preventing cumulative damage across the 3D structure.
3Speed
If large bias voltage difference is applied during IMS, then search operation speed is improved, but hot carrier injection effect increases causing data degradation
Solution Approach 1:
The patent changes the voltage parameter distribution by introducing multiple intermediate levels between the high and low word line voltages. This modification maintains the search operation speed while reducing the peak electric field strength that generates hot carriers, thereby preventing data degradation.
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 effectively reduces transverse electric field effects and hot carrier injection, thereby improving the stability of threshold voltages and reducing read failure in IMS memory cells, especially in high-density 3D memory devices.
Implementation Method 1
if the bias voltage difference between adjacent word lines is large, transverse electric field effects are induced to cause hot carrier injection (HCl) effect, which shifts the threshold voltages of the memory cells
Data Source
AI summary
The disclosure provides an in-memory search (IMS) memory cell, an IMS method and an IMS memory device. The IMS method comprises: encoding a search data and a storage data by a first IMS encoding into a first IMS encoded search data and a first IMS encoded storage data; encoding the first IMS encoded search data by a second IMS encoding into a plurality of search voltages; encoding the first IMS encoded storage data by the second IMS encoding into a plurality of threshold voltages of a plurality of memory cells of a plurality IMS memory cells of the IMS memory device; and searching the IMS memory cells by the search voltages to generate a search result.