Mask Read-Only Memory Cell Structure for Reliable Data Storage
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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 structures to maintain stored data without user programmability, while offering low cost and high reliability.
Innovation Solution
The development of a mask read-only memory with first and second state cell structures, featuring distinct gate and diffusion region configurations that allow for the differentiation of storing states during a read cycle using word line, read, and select line voltages, enabling accurate detection of stored data without user programmability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional non-volatile semiconductor memory cell structure is used, then the memory can be programmed by the user (OTP or MTP functionality), but it cannot function as a mask read-only memory cell with pre-recorded data and no user programmability
Solution Approach 1:
The memory cell is segmented into two distinct operational states with different physical structures: a first state cell structure for mask ROM operation and a second state cell structure for programmable operation. This segmentation allows the same memory cell to serve different functions based on its structural configuration, resolving the contradiction between user programmability and mask ROM data integrity.
Solution Approach 2:
The memory cell structure is designed to be universal, capable of functioning in multiple modes: as a mask read-only memory cell with pre-recorded data, or as a programmable memory cell (OTP or MTP). The cell can transition between these states, providing multi-functionality that satisfies both the need for data integrity and user programmability depending on the application requirement.
2Reliability
If mask read-only memory is used, then data storage reliability and cost-effectiveness are improved, but user programmability is lost
Solution Approach 1:
The memory cell structure is designed with dynamic characteristics, allowing it to transition between different operational states. The cell can be configured as a mask ROM cell with fixed data or reconfigured to accept user programming, providing adaptability while maintaining the reliability benefits of mask ROM in the appropriate state.
3Measurement precision
If higher voltages are used for read operations, then detection precision is improved, but power consumption increases and memory lifetime is reduced
Solution Approach 1:
The invention utilizes parameter changes in the memory cell structure, specifically changes in threshold voltage and conductivity type, to enable accurate data detection at lower read voltages. By modifying the physical parameters of the cell (through different gate structures and diffusion regions), the cell provides sufficient signal differentiation for reliable reading without requiring high voltage stress, thus reducing power consumption and extending memory lifetime.
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
The proposed solution effectively implements a mask read-only memory with two types of cell structures, allowing for reliable and cost-effective data storage and retrieval, ensuring data integrity and reducing power consumption by using lower voltages to enhance the memory's lifetime.
Implementation Method 1
The first diffusion region is formed in the surface of the substrate and located adjacent to a first side of the first gate structure for generating a first bit line voltage during the read cycle
Implementation Method 2
The first gate structure is formed on a surface of the substrate for receiving a word line voltage during a read cycle
Data Source
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”).