Memory Device Continuous Active Region Chip Area Optimization
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Solution Overview
Problem
Conventional integrated circuit (IC) designs for memory devices often result in wasted chip area due to the spacing required between adjacent memory cells, which can lead to inefficiencies in layout and manufacturing processes.
Innovation Solution
A memory device configuration where multiple strings of transistors and data storage elements are formed in a continuous active region, allowing adjacent data storage elements to be coupled to different bit lines, thereby eliminating the need for spacing and optimizing chip area usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If spacing is provided between adjacent memory cells, then manufacturing process variations are reduced, but chip area is wasted
Solution Approach 1:
The patent merges adjacent memory cells into a continuous active region, eliminating the spacing between cells. Multiple strings of transistors and data storage elements are formed in this continuous region, allowing adjacent cells to share common source/drain regions and reducing overall chip area while maintaining functional separation through selective gating.
Solution Approach 2:
The patent transitions from a two-dimensional layout with spaced cells to a three-dimensional structure where multiple transistor strings are vertically stacked or densely packed within a continuous active region. This dimensional change allows adjacent cells to be coupled to different bit lines while sharing common regions, eliminating wasted spacing area.
2Productivity
If spacing is provided between adjacent memory cells, then layout uniformity is improved, but manufacturing efficiency is reduced
Solution Approach 1:
The patent combines multiple memory cells into a continuous active region with shared source/drain structures, creating a more uniform layout that can be manufactured in fewer process steps. The continuous region allows for uniform material deposition and processing across the entire memory array, improving manufacturing efficiency.
3Area of stationary object
If multiple strings of transistors are formed in a continuous active region, then chip area is optimized, but device complexity increases
Solution Approach 1:
The patent segments the continuous active region into multiple transistor strings, each controlled by separate gate lines. This segmentation allows independent control of different cell groups while maintaining the area benefits of a continuous structure. The segmented approach manages complexity by organizing cells into controllable units.
Solution Approach 2:
The continuous active region serves multiple functions simultaneously: it provides the substrate for multiple transistor strings, creates shared source/drain regions for adjacent cells, and enables coupling to different bit lines. This multi-functionality reduces the need for separate structures, optimizing chip area while managing complexity through functional integration.
Data Source
AI summary
A memory device includes a set of word lines, first and second sets of bit lines, a first source line having first and second source line contacts, first and second strings of transistors electrically coupled in parallel between the first and second source line contacts of the source line, and first and second sets of data storage elements. Each word line in the set of word lines is electrically coupled to gates of a transistor in the first string and a corresponding transistor in the second string. The first set of data storage elements is electrically coupled between the first string of transistors and the first set of bit lines. The second set of data storage elements is electrically coupled between the second string of transistors and the second set of bit lines.