Word Line Width Variation for IC Refresh Stability
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Solution Overview
Problem
The increasing integration of integrated circuit devices leads to issues with word line resistance and pitch reduction, affecting refresh characteristics, and existing hydrogen passivation techniques for buried word line transistors are unreliable due to Vo-H bond breakage, causing unintended threshold voltage changes.
Innovation Solution
The integrated circuit device features a word line structure with varying widths over active regions and device isolation films, along with impurity regions and a gate dielectric film, where the second portion of the word line has a greater width than the first portion, and impurity regions are formed to reduce oxygen vacancies and stabilize the gate dielectric film, ensuring precise threshold voltage control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydrogen passivation is used to treat interface dangling bonds and oxygen vacancies in gate oxide, then refresh characteristics are enhanced, but threshold voltage becomes unstable due to Vo-H bond breakage during product use
Solution Approach 1:
The patent extracts the problematic hydrogen passivation process and replaces it with an oxygen plasma treatment process. By removing the hydrogen-based solution and substituting it with oxygen-based treatment, the invention eliminates the root cause of threshold voltage instability while maintaining the benefit of interface defect passivation.
Solution Approach 2:
The patent changes the chemical parameter of the passivation process from hydrogen-based to oxygen-based. This parameter change transforms the nature of the bonds formed at the interface, creating stable oxygen-silicon bonds instead of unstable hydrogen-oxygen bonds, thereby simultaneously achieving refresh enhancement and threshold voltage stability.
2Productivity
If word line pitch is reduced to increase integration degree, then device density increases, but word line resistance increases and refresh characteristics deteriorate
Solution Approach 1:
The patent applies local quality by creating different word line widths at different locations. The word line has a first width over active regions and a second, greater width over device isolation films. This local variation allows the word line to have lower resistance in isolation regions without occupying additional active area, thus maintaining high integration while improving refresh characteristics.
3Reliability
If word line width is increased to reduce resistance, then refresh characteristics improve, but device area increases
Solution Approach 1:
The patent implements local quality by varying the word line width according to location: narrower over active regions to minimize area, and wider over device isolation films to reduce resistance. This spatially differentiated approach allows the word line to optimize both area efficiency and electrical performance simultaneously.
Solution Approach 2:
The patent resolves the area-resistance tradeoff by introducing dimensional variation in the word line width. Instead of using a uniform width, the design transitions between different width dimensions at different spatial locations, effectively adding a dimensional degree of freedom to the word line structure.
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 reduces word line resistance, enhances reliability by stabilizing the threshold voltage, and improves the refresh characteristics of the integrated circuit device by eliminating oxygen vacancies and dangling bonds in the gate dielectric film.
Implementation Method 1
an impurity region arranged on the substrate and the device isolation film and contacting the gate dielectric film
Implementation Method 2
impurity regions are formed to reduce oxygen vacancies and stabilize the gate dielectric film
Data Source
AI summary
An integrated circuit device includes: a substrate including active regions; a device isolation film defining the active regions; a word line arranged over the active regions and the device isolation film and extending in a first horizontal direction; and a gate dielectric film arranged between the substrate and the word line and between the device isolation film and the word line, in which, in a second horizontal direction orthogonal to the first horizontal direction, a width of a second portion of the word line over the device isolation film is greater than a width of a first portion of the word line over the active regions. To manufacture the integrated circuit device, an impurity region is formed in the substrate and the device isolation film by implanting dopant ions into the substrate and the device isolation film, and a thickness of a portion of the impurity region is reduced.