Low-Voltage Programmable Fuse Using Tungsten Link
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
As integrated circuit geometries decrease, conventional electrically programmable fuses require additional power sources and circuit routing for programming at lower voltages, leading to non-persistent programming results, especially in applications like high-speed serial transceiver circuitry where 1.5V is required, and may cause damage to circuitry.
Innovation Solution
The development of fuse circuitry in integrated circuits using tungsten-based conductive materials for routing connections and via connections, along with a programming transistor and shallow trench isolation, allows for persistent programming at low voltages by reducing the resistance path and using silver, copper, gold, or aluminum for via connections, enabling effective programming at reduced voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrically programmable fuses are used in integrated circuits with decreased geometries, then the integrated circuit can be programmed, but additional power sources and circuit routing are required, increasing device complexity
Solution Approach 1:
The patent changes the material parameter from conventional copper to tungsten for the fuse link, which fundamentally alters the electrical resistance characteristics. This parameter change enables the fuse to be programmed persistently at low voltages without requiring additional power sources or complex circuit routing, thus resolving the contradiction between programming reliability and device complexity
Solution Approach 2:
The patent employs a composite material structure where tungsten is used for the fuse link and copper is used for the interconnect. This composite approach leverages the high melting point and low resistivity of tungsten for the fuse element while using copper's excellent conductivity for signal routing, achieving both persistent programming capability and low voltage operation without additional complexity
2Ease of manufacture
If conventional copper fuses are used for programming, then the programming process is simple, but the programming results are not persistent and may recover after short periods
Solution Approach 1:
The patent changes the critical parameter of fuse link material from copper to tungsten. Tungsten's higher melting point and different electrical characteristics enable persistent programming states that do not recover over time, while the overall manufacturing process remains compatible with standard semiconductor fabrication techniques, maintaining ease of manufacture
Solution Approach 2:
The patent applies local quality by using tungsten specifically for the fuse link portion where high temperature stability and persistent programming are needed, while copper is used for the interconnect portions where high conductivity is prioritized. This localized material assignment achieves programming persistence without complicating the overall manufacturing process
3Reliability
If high voltage is used to program electrically programmable fuses, then programming can be achieved, but it may cause damage to circuitry and is not compatible with low voltage integrated circuits
Solution Approach 1:
The patent changes the fuse link material to tungsten, which has a much higher melting point than copper. This parameter change allows the fuse to be programmed at low voltages (compatible with modern low-voltage integrated circuits) because the tungsten requires less current to achieve the necessary temperature for breaking the link, eliminating the need for high voltage that would damage other circuitry
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 solution enables persistent programming of electrically programmable fuses at low voltages, reducing the risk of time-dependent dielectric breakdown and ensuring reliable data storage even after cumulative read operations, thus addressing the limitations of conventional copper fuses which may recover after short periods.
Implementation Method 1
The first conductive material may include tungsten... enables persistent programming at low voltages by reducing the resistance path
Implementation Method 2
the above-mentioned fuse circuitry may be manufactured by forming a programming transistor in the substrate
Data Source
AI summary
An integrated circuit with electrically programmable fuse circuitry coupled to a programming transistor is provided. The programming transistor may be a metal-oxide-semiconductor transistor that is separated from other circuitry in an integrated circuit substrate with shallow trench isolation. The electrically programmable fuse circuitry may be formed in a second layer above the integrated circuit substrate using a conductive material which may be tungsten-based. This second layer may further include interconnect wires made from the same conductive material. The electrically programmable fuse may be coupled to the programming transistor through vias and routing paths in a fourth layer above the integrated circuit substrate. The routing paths in the fourth layer may be made from a conductive material which may be different than the fuse conductive material used to form the programmable fuse circuitry.