Flash Memory Device Source Line Segmentation
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Solution Overview
Problem
Conventional flash memory devices face challenges in implementing a structure where a block word line can pass through the cell array region due to the mesh-shaped pattern of the second source line, leading to increased device size and the need for multiple decoder switches.
Innovation Solution
The flash memory device modifies the source line shape and positions the discharge transistor between the cell array and X-decoder regions, allowing the block word line to pass through without additional metal lines, and enables sharing of pass transistors between cell array regions, thereby reducing the size of the X-decoder region by omitting decoder switches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the second source line is formed in a mesh-shaped pattern, then the source line can be connected to memory blocks, but it becomes difficult to implement a structure where the block word line passes through the cell array region
Solution Approach 1:
The second source line is divided into first line patterns arranged parallel to the block word line and a second line pattern that interconnects both ends of the first line patterns. This segmentation allows the block word line to pass through the cell array region between the first line patterns without interfering with the source line connection function.
Solution Approach 2:
The source line structure transitions from a traditional mesh pattern to a multi-layered configuration where the first line patterns are arranged in the first direction (parallel to block word line) and the second line pattern connects them in the second direction. This dimensional reorganization creates vertical space for the block word line to pass through.
2Ease of operation
If a decoder switch is required for each pass transistor, then the pass transistor can be controlled, but the memory device increases in size
Solution Approach 1:
The block word line serves multiple functions: it acts as a control signal line for the pass transistor and simultaneously functions as a metal line for signal transmission through the cell array region. This multi-functionality eliminates the need for separate decoder switches, reducing device size while maintaining control capability.
Solution Approach 2:
The control function previously requiring separate decoder switches is merged into the block word line structure itself. The block word line is integrated to directly control the pass transistor while maintaining its routing function, consolidating multiple functions into a single structural element.
Data Source
AI summary
A flash memory device is disclosed. The flash memory device includes: a cell array region; an X-decoder region arranged adjacent to the cell array region in a first direction; a discharge transistor region disposed between the cell array region and the X-decoder region; a first metal line formed to pass through the X-decoder region, the discharge transistor region, and the cell array region, and arranged to extend in the first direction; and a second metal line including a first line patterns arranged parallel to the first metal line between the first metal lines, and a second line pattern interconnecting both ends of the first line patterns and extending in a second direction crossing the first direction.