3D Memory Tier Mode Wordline Charge Retention
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Solution Overview
Problem
Three-dimensional (3D) memory devices experience power inefficiencies due to increased wordline capacitance, leading to slower read times and higher energy costs compared to two-dimensional (2D) memories, as they require frequent charging and discharging of wordlines during sequential access operations.
Innovation Solution
Implementing a tier mode that allows the memory to charge a wordline only once and maintain it charged for multiple accesses within the same tier, using a sub-block selector to toggle access to different portions without discharging the wordline until all portions in a tier have been accessed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If traditional 3D memory architecture is used with sequential wordline charging for each access, then memory density is increased, but power consumption increases and read time slows down due to repeated wordline charging and discharging
Solution Approach 1:
The wordline is charged in advance (pre-charged) before a series of access operations are performed. The control circuitry maintains the wordline in a charged state across multiple read or program operations, eliminating the need to recharge the wordline for each subsequent access. This preliminary charging action resolves the contradiction by allowing high memory density to be achieved without the penalty of repeated energy-intensive wordline charging cycles.
2Quantity of substance
If traditional 3D memory architecture is used with sequential wordline charging for each access, then memory density is increased, but read time slows down due to repeated wordline charging and discharging
Solution Approach 1:
The wordline is pre-charged and maintained in a charged state before and during multiple access operations. This eliminates the time-consuming charging and discharging cycles that would otherwise occur between each read or program operation, significantly reducing total access time while preserving the high density benefits of 3D memory architecture.
3Reliability
If wordline is charged and discharged for each access operation in 3D memory, then proper memory operation is maintained, but energy efficiency deteriorates compared to 2D memories
Solution Approach 1:
The wordline is charged in advance and maintained charged across multiple operations, eliminating repeated charging cycles. The control circuitry intelligently manages the wordline state, charging it once before a sequence of read or program operations and maintaining it charged throughout, thereby achieving energy efficiency comparable to or better than 2D memories while preserving reliable memory operation.
Solution Approach 2:
The wordline remains continuously charged during a sequence of access operations rather than being discharged and recharged between each operation. This continuous charged state eliminates energy loss from repeated charging cycles while maintaining proper memory operation, significantly improving energy efficiency without sacrificing operational reliability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly reduces energy consumption and improves read time efficiency by spreading the energy cost across multiple access operations, achieving faster and more energy-efficient data retrieval in 3D memory devices.
Implementation Method 1
the wordline capacitance (CWL) increases significantly over comparable 2D structures
Data Source
AI summary
Tier access mode for three dimensional (3D) memory devices. A 3D memory device has multiple memory elements that are each addressable by a two dimensional address including a wordline address and a bitline address, and a third dimension with a sub-block selector indicating one of multiple portions of a tier of memory elements in the memory device. A memory controller generates a memory access command, such as read or program, to access a first portion of the memory and sends the command to the memory device. The memory device charges a first wordline and a first sub-block in response to receiving the command. For a consecutive access command to access a second portion of the memory, the memory device maintains the first wordline charged without discharging it, and charges a second sub-block selector in response to the consecutive command.