Semiconductor Device Dual Trench Isolation Tungsten Deposition
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Solution Overview
Problem
In semiconductor devices with deep trench isolation structures, wider trenches facilitate tungsten film deposition on the bottom surface but can lead to gaps, necessitating additional lead-out electrodes to prevent exposure and ensure electrical coupling.
Innovation Solution
The semiconductor device employs a dual trench structure with a wider first trench and a narrower second trench, where the tungsten film is formed to close the opening end of the narrower trench, allowing for electrical coupling without the need for a lead-out electrode by using an etch back process to maintain the film within the trench.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the trench width is increased to facilitate tungsten film deposition on the bottom surface, then the ease of manufacture is improved, but gaps are more easily formed and exposed in the deep trench
Solution Approach 1:
The element isolation unit is divided into two distinct units: a first element isolation unit with a wider trench for facilitating tungsten film deposition, and a second element isolation unit with a narrower trench for preventing gap exposure. This segmentation allows each unit to optimize for its specific function without compromise.
Solution Approach 2:
Different regions of the element isolation structure are given different widths tailored to their specific requirements. The first element isolation unit has a larger width optimized for tungsten film formation, while the second element isolation unit has a smaller width optimized for gap prevention, allowing each local region to have the quality needed for its purpose.
2Reliability
If a lead-out electrode is added to prevent gap exposure and ensure electrical coupling, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The second element isolation unit serves multiple functions: it acts as an isolation structure, prevents gap exposure through its narrower geometry, and provides electrical coupling to the semiconductor substrate. By making the element isolation unit itself multi-functional, the need for separate lead-out electrodes is eliminated.
Solution Approach 2:
The functions of gap prevention and electrical coupling are merged into the second element isolation unit by forming a conductor unit within it. This combines the isolation function with the electrical coupling function in a single integrated structure, eliminating the need for separate lead-out electrode components.
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 eliminates the requirement for additional lead-out electrodes, ensuring reliable electrical coupling and preventing gap exposure in the narrower trenches while maintaining adequate tungsten film formation in wider trenches.
Implementation Method 1
a tungsten film is formed also in the deep trench, as the conductor unit
Implementation Method 2
by performing an etch back process for the conductive film and removing a part of the conductive film positioned above an upper surface of the semiconductor substrate while remaining a part of the conductive film positioned in each of the first trench and the second trench
Data Source
AI summary
In an element isolation region defining an element formation region, there is formed an element isolation unit including an element isolation unit and the other element isolation unit. The other element isolation unit is arranged in a direction intersecting a direction in which the element isolation unit extends from the element isolation unit. The element isolation unit includes a sidewall oxide film formed in a trench, a titanium film, a titanium nitride film, and a tungsten film. The tungsten film is formed to cover the bottom surface of a trench in the element isolation unit and to close an opening end of a trench in the other element isolation unit. A plug is formed in contact with the tungsten film of the element isolation unit.