Pulsed Control Line Biasing for Memory Voltage Generation
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Solution Overview
Problem
The operation of semiconductor memory devices faces challenges related to space, power consumption, and performance due to the use of many different voltages, which can lead to inefficiencies in programming, verifying, and reading operations, particularly in 3D memory structures where charge pumps consume significant space and power, and voltage settling times are delayed.
Innovation Solution
The use of rectangular waveforms with varying duty cycles to provide different effective voltages for control lines in memory devices, such as word lines, bit lines, and source lines, during programming, verifying, and reading operations, where the duty cycle is adjusted based on the assigned data state or programming speed category, allowing for efficient voltage application through pulse modification or counting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If charge pumps are used to generate multiple voltages in 3D memory structures, then the required voltage levels for programming, verifying, and reading operations are achieved, but the device occupies significant space and consumes excessive power
Solution Approach 1:
The patent merges the voltage generation function into the control lines themselves by applying pulsed voltage signals directly to word lines, bit lines, and source lines. This eliminates the need for separate charge pump circuits, thereby reducing device space and power consumption while maintaining the required voltage levels for memory operations
Solution Approach 2:
The control lines serve multiple functions: they simultaneously perform data programming, verification, and reading operations by dynamically adjusting the pulse width and amplitude of voltage signals. This multi-functionality replaces the need for dedicated circuits for each operation type, reducing overall device complexity
2Productivity
If multiple different voltages are applied to control lines for different operations, then programming, verifying, and reading operations can be performed, but voltage settling times are delayed and operational efficiency is reduced
Solution Approach 1:
The patent employs periodic pulsed voltage signals with varying pulse widths to perform different operations. By using periodic action instead of sustained voltage levels, the control lines can quickly transition between states, reducing voltage settling time and improving operational efficiency
Solution Approach 2:
The control line voltages are dynamically adjusted by modifying pulse width and amplitude based on the current operation phase (programming, verification, or reading). This dynamic control allows rapid voltage transitions and eliminates the delays associated with switching between multiple static voltage levels
3Speed
If uniform voltage application is used across all memory cells, then programming speed is enhanced and threshold voltage distributions become narrower, but the ability to perform different operations (programming, verifying, reading) is limited
Solution Approach 1:
The patent changes the parameters of the voltage signals (pulse width, amplitude, and timing) applied to control lines to perform different operations. By varying these parameters uniformly across all memory cells, the system achieves both high programming speed and operational versatility without requiring different voltage levels for different cell groups
Data Source
AI summary
In one aspect, a voltage is provided as a rectangular waveform in which the duty cycle is varied to provide different effective voltages. These voltages may be applied to various control lines in a memory device such as a word line, bit line and/or source line, in a program, verify, read or erase operation. In some cases, the duty cycle is a function of programming data of a memory cell such as an assigned data state or a programming speed category. The duty cycle could also be a function of a programming phase or other criterion. The duty cycle can be varied by modifying the duration and separation of the pulses of the waveform or by pulse counting, in which a specified number of pulses are passed in a time period.