OTP Memory Cell with Bipolar Transistor and Fusable Element
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
There is a demand for higher storage density and reliability in one-time programmable (OTP) memory cells that are compatible with standard manufacturing techniques, such as CMOS processes, while maintaining non-volatile memory capabilities.
Innovation Solution
The integration of a fusable element, such as a fuse or anti-fuse, with a bipolar transistor in a memory cell configuration, where the fusable element is accompanied by an oxide film that can be irreversibly modified by a programming voltage, and a grid of wordlines and bitlines to program and read the memory cells effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If higher storage density is implemented in OTP memory cells, then the number of memory cells per area increases, but manufacturing complexity and reliability challenges increase
Solution Approach 1:
The patent combines the fusable element with a bipolar transistor into an integrated memory cell structure. The bipolar transistor is formed using the same semiconductor regions (emitter, base, collector) that constitute the fusable element, merging two functional components into a single integrated unit that achieves high storage density while maintaining manufacturing compatibility with standard CMOS processes
Solution Approach 2:
The bipolar transistor serves multiple functions: it acts as a selection device for addressing memory cells, provides signal amplification during read operations, and enables low-voltage reading. This multi-functionality reduces the need for additional separate components, thereby increasing storage density without proportionally increasing manufacturing complexity
2Quantity of substance
If higher storage density is implemented in OTP memory cells, then the number of memory cells per area increases, but reliability may deteriorate
Solution Approach 1:
The bipolar transistor configuration provides inherent protection against programming errors and degradation. The transistor's gain provides noise margin and error detection capability, cushioning against potential reliability issues before they manifest as failures. The structured voltage application through the transistor prevents accidental programming during normal operation
Solution Approach 2:
The fusable element is designed as a disposable component that is intentionally made vulnerable to controlled breakdown. The element can be reliably programmed once through oxide breakdown and then maintains its state indefinitely, trading the durability of the programming mechanism for the permanence of the stored state, thereby improving overall system reliability
3Ease of manufacture
If standard manufacturing techniques like CMOS process are used, then ease of manufacture improves, but achieving high storage density and reliability becomes more challenging
Solution Approach 1:
The patent utilizes parameter changes in the semiconductor fabrication process, specifically varying doping concentrations and layer thicknesses, to create the bipolar transistor structure within standard CMOS process capabilities. By adjusting these parameters, the invention achieves high storage density while remaining compatible with existing manufacturing techniques
Solution Approach 2:
The memory cell employs composite material structures combining different semiconductor regions (n-type and p-type doped regions) to form the bipolar transistor. This composite approach allows the device to be fabricated using standard CMOS processes that already incorporate multiple material layers and doping steps, achieving high density without requiring entirely new manufacturing techniques
4Ease of manufacture
If standard manufacturing techniques like CMOS process are used, then ease of manufacture improves, but achieving high reliability becomes more challenging
Solution Approach 1:
The bipolar transistor structure is self-forming through the semiconductor fabrication process itself. The emitter, base, and collector regions are created as inherent parts of the CMOS manufacturing sequence, with the fusable element integrated into the same structure. This self-service approach ensures that reliability-critical components are formed using the same controlled processes that ensure manufacturing consistency
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 configuration allows for higher storage density and reliability in OTP memory arrays, ensuring compatibility with standard manufacturing techniques and enabling efficient programming and reading of memory cells without power supply.
Implementation Method 1
Fuses or anti-fuses may be irreversibly modified by applying a programming voltage, for example through breakdown of an oxide, thus programming the memory
Data Source
AI summary
Memory cells and corresponding memory arrays are provided. The memory cell comprises a fusable element and a bipolar transistor arranged adjacent to the fusable element.