3D CAM Block Vertical String Programming for Data Retention
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Solution Overview
Problem
The data stored in content addressable memory (CAM) blocks of 3-dimensional semiconductor devices can become corrupted due to high temperatures generated during manufacturing processes, affecting the operation setting values such as bad block repair information and bias information.
Innovation Solution
A semiconductor device with a CAM block featuring vertical strings electrically coupled to word lines, where a control circuit simultaneously applies a program voltage to a selected word line and adjacent word lines to program CAM cells connected by a charge trap layer, enhancing the retention characteristics of the CAM cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If data is stored in CAM blocks of 3-dimensional semiconductor devices, then operation setting values can be stored and retrieved, but the data can become corrupted due to high temperatures generated during manufacturing processes
Solution Approach 1:
The patent applies preliminary programming to CAM cells adjacent to the selected CAM cell before the actual programming operation. By pre-programming neighboring CAM cells with valid data, the invention ensures that even if temperature-induced corruption occurs during manufacturing, the adjacent pre-programmed cells can provide backup information, thereby preventing data corruption and improving reliability against thermal effects
Solution Approach 2:
The invention creates a protective buffer by programming adjacent CAM cells in advance. This cushioning approach ensures that if the selected CAM cell data becomes corrupted due to high temperature exposure during manufacturing, the surrounding pre-programmed cells serve as a protective buffer, maintaining data integrity and preventing complete data loss
2Reliability
If a program voltage is applied to a selected word line to program CAM cells, then the selected CAM cells can be programmed, but adjacent CAM cells may not be programmed, leaving them vulnerable to data corruption
Solution Approach 1:
The patent merges the programming operation to include both the selected CAM cell and its adjacent CAM cells simultaneously. By extending the program voltage application to cover neighboring word lines along with the selected word line, the invention ensures that adjacent CAM cells are also programmed in the same operation, eliminating data integrity vulnerabilities without requiring separate programming steps
Solution Approach 2:
The programming mechanism is enhanced to serve multiple functions: it programs the selected CAM cell while simultaneously programming adjacent CAM cells. This multi-functional approach allows a single programming operation to accomplish both the primary programming task and the protective pre-programming of neighboring cells, improving data integrity without proportionally increasing device complexity
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 improves the retention characteristics of CAM cells, reducing the impact of temperature-related changes and enhancing the reliability of operation setting values, thereby improving the overall reliability of the semiconductor device.
Implementation Method 1
A 3-dimensional semiconductor device includes a plurality of vertical strings, where the vertical strings have a generally perpendicular configuration with respect to a semiconductor substrate. The memory cells in the vertical strings do not have the floating structure that is typically used in a 2-dimensional semiconductor device. A 3-dimensional semiconductor devices uses a charge trap structure.
Data Source
AI summary
The semiconductor device includes a CAM block including a plurality of vertical strings having a perpendicular configuration with respect to a semiconductor substrate, wherein each of the plurality of vertical strings is electrically coupled to a plurality of word lines and each of the plurality of word lines is electrically coupled to a plurality of CAM cells, a peripheral circuit configured to program CAM cells selected from the plurality of CAM cells, and a control circuit configured to issue at least one command to the peripheral circuit to simultaneously apply a program voltage to an nth word line, an n−1th word line and an n+1th word line to simultaneously program CAM cells electrically coupled to the n−1th word line, the nth word line and the n+1th word line, wherein the n−1th word line and an n+1th word line are adjacent to the nth word line and the selected CAM cells are electrically coupled to the nth word line.