Bleeder Circuits for Stabilizing Floating Column Selection Lines
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Solution Overview
Problem
In semiconductor memory devices, broken Y-address selection wires can go undetected during manufacturing, leading to data reliability issues due to signal disconnection, which existing redundancy techniques may not fully address, especially when the broken wire is electrically floating and affects local input/output lines.
Innovation Solution
The implementation of CS bleeder circuits that stabilize the voltage of defective column selection lines by coupling CS bleeder transistors to YS transistors via a YS transistor channel, ensuring a stable voltage even when the column selection line is open, thereby preventing data overwrites.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If redundancy wires for address lines are introduced to replace broken wires, then data reliability is improved, but the electrically floating state of broken YS wires can still cause data overwrites on local input/output lines
Solution Approach 1:
A pull-down resistor is introduced as an intermediary component connected between the column selection line and ground. This resistor acts as a mediator that provides a controlled electrical path to stabilize the floating potential of broken YS wires, preventing them from assuming random voltage levels that could cause data overwrites while maintaining the redundancy wire structure
Solution Approach 2:
The invention converts the harmful effect of the electrically floating broken wire into a beneficial stabilization mechanism. By intentionally adding a pull-down resistor, the floating state that causes random voltage levels is transformed into a controlled state where the resistor actively pulls the voltage to a known low level, preventing data corruption
2Device complexity
If the broken YS wire is left in electrically floating state, then manufacturing complexity is reduced, but voltage instability causes data overwrites and reliability issues
Solution Approach 1:
The solution segments the column selection line into two independent parts: the main signal path and the stabilization path. The pull-down resistor is connected only to the portion of the line that may become floating due to breaks, providing localized stabilization without affecting the overall signal integrity or requiring complete redesign of the address line architecture
Solution Approach 2:
The pull-down resistor is a simple, inexpensive passive component that provides effective stabilization. It is a basic electronic component that can be easily integrated into the existing memory structure without adding significant complexity, serving as a low-cost solution to the floating wire problem
Data Source
AI summary
Apparatuses for controlling defective bit lines in a semiconductor device are described. An example apparatus includes: a first region including a plurality of bit lines, a plurality of word lines and a plurality of memory cells, each memory cell is coupled to an associated bit line and an associated word line; a second region including a plurality of sense amplifiers, each sense amplifier includes a sense node and a column selection switch coupled to the sense node; a third region including a plurality of bleeder circuits, and disposed between the first and second regions; and a plurality of column selection lines. Each bit line from the first region to the second region is coupled to the sense node of an associated one of the plurality of sense amplifiers, and each column selection line from the column selection switch is coupled to an associated bleeder circuit.