OTP Memory Sensing via Dual-Voltage Breakdown Detection
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Solution Overview
Problem
There is a need for reliable detection of soft breakdowns, close soft breakdowns, and hard breakdowns in high-dielectric-constant metal-gate one-time-programming (OTP) memory devices with thin gate dielectric layers, as existing methods struggle to differentiate between these states effectively.
Innovation Solution
A method and apparatus for sensing soft and hard breakdowns in memory cells by reading drain currents at specific gate voltages, comparing them to predetermined values, and generating indications of either hard or soft breakdowns based on these readings, utilizing two distinct gate voltage conditions to distinguish between the states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a thin gate dielectric layer is used in logic HK-MG OTP memory devices, then device scaling and integration density are improved, but soft breakdowns become more frequent and reliable detection becomes difficult
Solution Approach 1:
The sensing process is segmented into two distinct stages: first sensing at a first gate voltage to detect hard breakdowns, and second sensing at a second gate voltage to detect soft breakdowns. This segmentation allows reliable detection of both breakdown types without interference, resolving the reliability issue caused by frequent soft breakdowns in thin gate dielectric devices.
Solution Approach 2:
The method changes the gate voltage parameter between two distinct sensing operations. The first sensing uses a first gate voltage condition, and the second sensing uses a second gate voltage condition. This parameter change enables differentiation between soft and hard breakdowns, improving detection reliability in thin gate dielectric devices where soft breakdowns are frequent.
2Ease of operation
If conventional single-voltage sensing is used, then device operation is simple, but differentiation between soft breakdowns and hard breakdowns is unreliable
Solution Approach 1:
The sensing method dynamically adjusts the gate voltage between two distinct conditions: a first gate voltage for initial sensing and a second gate voltage for follow-up sensing. This dynamic voltage adjustment enables accurate differentiation between soft and hard breakdowns while maintaining operational simplicity through automated sequential sensing.
Solution Approach 2:
The method uses feedback from the first sensing operation to determine whether to perform the second sensing. If the first drain current indicates a soft breakdown condition, the system feeds back to trigger a second sensing at a different gate voltage to confirm and differentiate the breakdown state, improving measurement precision without significantly complicating operation.
3Manufacturing precision
If gate dielectric thickness is reduced for scaling, then manufacturing density increases, but the sensing window for hard and soft breakdowns overlaps making detection unreliable
Solution Approach 1:
The method introduces a new dimension for sensing by using two distinct gate voltage conditions instead of relying solely on drain current magnitude at a single voltage. This dimensional change in the sensing approach separates the sensing windows for soft and hard breakdowns, making detection reliable even in scaled devices with thin gate dielectrics where traditional single-voltage sensing fails.
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 provides a reliable means to differentiate between soft and hard breakdowns in OTP memory cells, enhancing the yield and reliability of memory devices by improving bake retention performance without requiring additional fabrication steps or masks, thus expanding the sensing window and improving the overall reliability of OTP memory arrays.
Implementation Method 1
High-dielectric-constant (HK) metal-gate (MG) one-time-programming (OTP) memory devices with thin gate dielectric layers have been used as logic devices in semiconductor integrated circuits. A typical logic HK-MG OTP memory device may experience a non-breakdown or soft breakdown or a hard breakdown.
Data Source
AI summary
In a one-time-programming (OTP) memory cell, dual-voltage sensing is utilized to determine whether the memory cell has experienced a non/soft breakdown or a hard breakdown. The drain current of the memory cell is read when the gate voltage is at a first predetermined voltage, and if the read drain current is greater than a predetermined current level, then a hard breakdown is detected. One or more additional readings of the current may be obtained to determine that a hard breakdown has occurred. If the read drain current is less than the predetermined current level, then a non/soft breakdown is detected. The threshold voltage of the memory cell may be shifted, and a second reading of the drain current may be obtained when the gate voltage is at a second predetermined voltage in case the memory cell experiences a non/soft breakdown.