Memory Device Program Voltage Compensation for Block Oxide Thinning
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Solution Overview
Problem
Memory devices face challenges in optimizing program speed due to variations in block oxide thickness, leading to inconsistent programming times and risks of over-programming or under-programming across different memory holes within a block.
Innovation Solution
The solution involves optimizing the initial program voltage based on measured program speeds, which are influenced by the thickness of the blocking oxide layer, by acquiring program speeds from central and edge sub-blocks and interpolating or extrapolating these values to determine optimal voltages for intermediate sub-blocks, thereby ensuring uniform programming across the block.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed initial program voltage is used for all sub-blocks, then the device complexity is reduced, but the manufacturing precision deteriorates due to block oxide thickness variations
Solution Approach 1:
The patent applies local quality by setting different initial program voltages for different sub-blocks based on their position within the block. Edge sub-blocks receive different voltage levels than central sub-blocks to compensate for the non-uniform block oxide thickness that occurs during fabrication, ensuring each region is programmed with the appropriate voltage for its specific characteristics.
Solution Approach 2:
The patent changes the program voltage parameter dynamically based on sub-block position. By adjusting the initial program voltage level according to whether a sub-block is located at the edge or center of a block, the system compensates for manufacturing variations in block oxide thickness and achieves uniform programming across the entire block.
2Manufacturing precision
If the program voltage is increased to compensate for thick block oxide, then the manufacturing precision improves, but the reliability deteriorates due to over-programming risk
Solution Approach 1:
The patent prevents over-programming by applying different voltage levels to different sub-blocks. Edge sub-blocks with thicker block oxide receive higher initial program voltages, while central sub-blocks with thinner block oxide receive lower voltages, ensuring each region is programmed appropriately without exceeding the required threshold.
Solution Approach 2:
The patent uses a controlled excessive action approach by applying higher initial program voltages only to edge sub-blocks where it is necessary to penetrate the thicker block oxide, while using lower voltages for central sub-blocks where excessive voltage would cause over-programming.
3Reliability
If the program voltage is decreased to prevent over-programming, then the reliability improves, but the manufacturing precision deteriorates due to under-programming risk
Solution Approach 1:
The patent ensures programming completeness by applying higher initial program voltages to edge sub-blocks that have thicker block oxide and require more energy to achieve proper programming, while using lower voltages for central sub-blocks where the thinner block oxide would otherwise lead to over-programming.
4Manufacturing precision
If additional program loops are executed to ensure complete programming, then the manufacturing precision improves, but the productivity deteriorates
Solution Approach 1:
The patent applies preliminary action by setting the initial program voltage appropriately before the programming process begins. By pre-configuring the correct voltage level based on sub-block position, the system ensures complete programming in the first pass without requiring additional corrective program loops, thereby maintaining high productivity.
Solution Approach 2:
The patent uses feedback from block oxide thickness measurements to determine the appropriate initial program voltage for each sub-block. This feedback mechanism allows the system to adjust voltage levels based on actual manufacturing variations, ensuring complete programming while minimizing the number of required program loops.
Data Source
AI summary
Techniques are provided for optimizing a program operation in a memory device to compensate for program speed variations due to block oxide thinning. In one approach, during a program operation, a program voltage which indicates program speed is acquired from sub-blocks with the highest and lowest program speeds. An initial program voltage for intermediate sub-blocks can be determined based on the acquired program voltages and the positions of the intermediate sub-blocks. The technique can accommodate a loss of one or both acquired program voltages if the programming is interrupted. In another approach, a program voltage which indicates program speed is acquired from one sub-block, and for a later-programmed sub-block, an appropriate offset is located from a table and summed with the acquired program voltage to determine an optimum initial program voltage.