Interleaved String Driver Layout With Gated LDD Isolation
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Solution Overview
Problem
Current memory devices face challenges in reducing the pitch between string drivers to achieve smaller and denser memory systems without compromising leakage current and breakdown voltage.
Innovation Solution
The implementation of interleaved string drivers with narrow active regions and gated lightly doped drains (LDDs) using deep trench isolation structures, which reduces the effective distance between opposing contacts and allows for a smaller pitch while maintaining optimal electrical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the pitch between string drivers is reduced to make memory devices smaller and denser, then the device size is reduced, but the leakage current increases and breakdown voltage decreases
Solution Approach 1:
The string driver structure is segmented into multiple components: the string driver body, the contact region, and the isolation region. This segmentation allows the pitch to be reduced by optimizing each segment's dimensions independently while maintaining electrical performance through proper design of the contact and isolation regions.
Solution Approach 2:
The patent applies local quality by creating a narrow active region around the contact area with specific doping characteristics. The lightly doped drain (LDD) region is positioned and dimensioned locally to provide electrical isolation and control leakage current specifically where needed, without affecting the overall pitch reduction.
2Productivity
If the pitch between string drivers is reduced, then manufacturing density increases, but maintaining optimal electrical performance becomes difficult
Solution Approach 1:
The patent changes critical parameters including the contact width, the LDD region dimensions, and the doping concentration in specific regions. By adjusting these parameters, the pitch can be reduced while maintaining electrical performance - the LDD region's doping level and geometry are optimized to control leakage current at the smaller pitch.
Solution Approach 2:
The lightly doped drain (LDD) region acts as an intermediary structure between the string driver contacts. This intermediate region provides electrical isolation and controls leakage current, enabling pitch reduction while maintaining proper electrical performance through its specific doping characteristics and geometric positioning.
Data Source
AI summary
A memory device includes a first string driver circuit and a second string driver circuit that are disposed laterally adjacent to each other in a length direction of a memory subsystem. The first and the second string driver circuits are disposed in an interleaved layout configuration such that the first connections of the first string driver are offset from the second connections of the second string driver in a width direction. For a same effective distance between the corresponding opposing first and second connections, a first pitch length corresponding to the interleaved layout configuration of the first and second string drivers is less by a predetermined reduction amount than a second pitch length between the first and second string drivers when disposed in a non-interleaved layout configuration in which each of the first connections is in-line with the corresponding second connection.