Split-Thickness Dielectric for One-Time Programmable Semiconductor Devices
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Solution Overview
Problem
Conventional one-time programmable (OTP) semiconductor devices are larger than desired, leading to reliability and manufacturing cost issues due to uncontrolled conductive path formation and impedance variations in programmed states, which require additional die space and high voltage sensing circuitry.
Innovation Solution
The integration of polysilicon-gate transistors with split-thickness dielectric and independently programmable NFET structures allows for controlled programming region size and impedance distribution, reducing the need for high voltage sensing circuits and redundancy techniques by using a common electrode to program and sense OTP device states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional OTP devices use a wide single channel interface with two different gate dielectric thicknesses, then programming functionality is achieved, but device area increases and reliability decreases
Solution Approach 1:
The gate dielectric is segmented into two distinct thickness regions: a first thickness in the programming region and a second thickness in the non-programming region. This segmentation allows controlled breakdown only in the thinner programming region, enabling reliable OTP functionality while reducing overall device area compared to conventional wide single-channel interfaces.
Solution Approach 2:
The gate dielectric exhibits local quality variations with different thicknesses in different regions. The thinner dielectric in the programming region facilitates controlled breakdown for programming, while the thicker dielectric in the non-programming region maintains device reliability and prevents unintended breakdown, thus improving reliability without requiring larger device area.
2Measurement precision
If conventional OTP devices use uncontrolled conductive path formation, then programming is achieved, but impedance distribution widens and sensing precision deteriorates
Solution Approach 1:
By creating a localized thin dielectric region specifically in the programming area, the breakdown process is confined to this specific location. This local quality variation ensures that conductive paths form only where intended, providing precise control over programming location and resulting in narrow impedance distribution for improved sensing precision.
Solution Approach 2:
The gate dielectric thickness parameter is changed spatially across the device structure. The thinner thickness in the programming region lowers the breakdown voltage threshold locally, enabling controlled breakdown at specific locations. This parameter variation ensures precise conductive path formation while maintaining narrow impedance distribution, thereby improving both manufacturing precision and measurement precision.
3Reliability
If conventional OTP devices add high voltage sensing circuitry and redundancy techniques, then sensing reliability improves, but device area and manufacturing cost increase
Solution Approach 1:
The gate dielectric structure itself provides the sensing function through its inherent thickness variation. The thin programming region dielectric creates a naturally differentiated impedance state after breakdown, which can be sensed without requiring additional high voltage sensing circuitry. The structure serves both programming and sensing functions, eliminating the need for separate sensing components and reducing die space.
Solution Approach 2:
The spatial variation in gate dielectric thickness creates inherently differentiated electrical parameters (impedance, breakdown voltage) between programmed and unprogrammed states. This parameter differentiation enables reliable sensing through simple voltage measurement without requiring complex high voltage sensing circuitry, thus improving sensing reliability while minimizing additional die space requirements.
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 approach results in a smaller, more reliable OTP device with reduced manufacturing costs and higher device density, enabling efficient implementation of OTP functions in integrated circuits.
Implementation Method 1
The thin portion of gate dielectric can be made to destructively break down and form a conductive path from gate to channel
Data Source
AI summary
According to one disclosed embodiment, an integrated one-time programmable (OTP) semiconductor device pair includes a split-thickness dielectric under an electrode and over an isolation region formed in a doped semiconductor substrate, where a reduced-thickness center portion of the dielectric forms, in conjunction with the isolation region, programming regions of the OTP semiconductor device pair, and where the thicker, outer portions of the dielectric form dielectrics for transistor structures. In one embodiment, the split-thickness dielectric comprises a gate dielectric. In one embodiment, multiple OTP semiconductor device pairs are formed in an array that minimizes the number of connections required to program and sense states of specific OTP cells.