Mask Read-Only Memory Cell Structure Design
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Solution Overview
Problem
Conventional non-volatile semiconductor memory cells are not capable of functioning as mask read-only memory cells, which require specific cell structures to maintain stored data without user programmability after manufacturing, posing challenges in achieving low cost, high reliability, and high capability in electronic devices.
Innovation Solution
The development of a mask read-only memory with first and second state cell structures, featuring specific gate and diffusion region configurations on a substrate, allowing for distinct bit line and read voltages during a read cycle to differentiate and detect stored states, thereby ensuring data integrity and unalterability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional non-volatile semiconductor memory cell structures are used, then the memory can be programmed by users (OTP or MTP functionality), but the memory cannot function as mask read-only memory with unalterable data
Solution Approach 1:
The patent applies local quality by creating two distinct cell structure types within the same memory array: first type cell structures with a first configuration and second type cell structures with a second configuration. Each type has specific structural characteristics that determine its read-out behavior, allowing some cells to represent logic '0' and others to represent logic '1' in a mask read-only memory fashion. This local structural differentiation enables unalterable data storage while maintaining overall memory functionality.
Solution Approach 2:
The memory array is segmented into multiple first type cell structures and multiple second type cell structures. This segmentation allows the memory to be divided into functional units with different structural configurations, enabling the mask read-only memory operation where data is determined by the physical structure rather than user programming.
2Reliability
If mask read-only memory with specific cell structures is implemented, then data reliability and unalterability are improved, but device complexity increases due to multiple gate and diffusion region configurations
Solution Approach 1:
The patent merges multiple functions into the cell structure by integrating the storage function with the read-out function in a single structure. The gate structures and diffusion regions serve both as selection elements and as data representation elements. This merging reduces the need for separate programming circuits and control mechanisms, thereby managing complexity while ensuring data integrity.
Solution Approach 2:
The cell structures are designed with multi-functionality where the same basic components (gates, diffusion regions) serve multiple purposes: word line selection, bit line selection, and data state representation. This universality allows the memory to operate as mask read-only memory without requiring entirely separate structures for different functions, thus controlling complexity while maintaining high reliability.
3Measurement precision
If multiple gate structures and diffusion regions are configured for mask read-only memory, then accurate detection of logic states is enabled, but manufacturing precision requirements increase
Solution Approach 1:
The patent employs equipotentiality by designing the gate structures and diffusion regions with symmetric and balanced configurations. The first and second type cell structures use comparable structural elements arranged in consistent patterns, ensuring that manufacturing variations affect all cells similarly. This approach reduces the impact of fabrication tolerances on logic state detection accuracy.
Solution Approach 2:
The patent uses parameter changes by varying the structural configuration (rather than dimensional precision) to differentiate between logic states. The first type and second type cell structures differ in their structural arrangement, which can be achieved through standard manufacturing processes. This approach shifts the differentiation criterion from precise dimensional control to topological configuration, reducing manufacturing precision requirements while maintaining detection accuracy.
Data Source
Figure 1
Figure 2A~2C
Figure 3A~3C
AI summary
A novel mask read-only memory is provided. After the mask read-only memory leaves the factory, the mask read-only memory has two types of cell structures. The first type cell structure records a first storing state (e.g. the logic state "1 "), and the second type cell structure records a second storing state (the logic state "0").