Semiconductor Contact Hole Gap Filling via Damascene Trench
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Solution Overview
Problem
As semiconductor devices shrink, the narrow width of contact holes leads to inadequate gap filling with conductive layers, causing adhesion issues and overhang, resulting in contact shorts and voids, which decrease yield and lead to erase failures.
Innovation Solution
A damascene pattern comprising a contact hole and a trench is formed, with a wider upper entry region to prevent overhang, allowing for simultaneous formation of contact plugs and bit lines, using insulating layers and etch-stop layers to manage the gap filling process effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the contact hole width is reduced to maintain device scaling, then device density is improved, but gap filling quality deteriorates causing voids and poor contact
Solution Approach 1:
The patent introduces a trench structure adjacent to the contact hole, creating a multi-dimensional damascene pattern. This additional dimension provides a wider upper entry region that prevents overhang during gap filling, while the trench is later removed to leave the contact hole intact with improved filling quality
Solution Approach 2:
The patent segments the contact hole structure by introducing a separate trench region that is formed, filled, and then removed. This segmentation allows the temporary creation of a wider opening for improved gap filling, while the final structure maintains the original contact hole dimensions
2Reliability
If a titanium-based barrier metal layer is formed to prevent adhesion, then adhesion control is improved, but overhang occurs at the upper entry causing voids
Solution Approach 1:
The patent adds a trench dimension adjacent to the contact hole, creating a wider combined upper entry region. This additional space accommodates the titanium barrier metal layer without causing overhang, as the barrier layer can be deposited in the wider region and then selectively removed from the trench portion
3Shape
If the upper entry of the contact hole is narrowed to prevent overhang, then overhang is reduced, but gap filling becomes inadequate creating voids
Solution Approach 1:
The patent inverts the conventional approach by first narrowing the contact hole upper entry (which would normally cause filling problems), then introducing a trench to provide the necessary width for proper gap filling. The trench is subsequently removed, leaving the narrow contact hole properly filled
Data Source
AI summary
The present invention relates to a method of fabricating a semiconductor device. According to the method, a first insulating layer having a contact hole formed therein is formed over a semiconductor substrate. A second insulating layer is gap filled within the contact hole. A third insulating layer having a trench formed therein is formed over the semiconductor substrate including the contact hole. The second insulating layer gap filled within the contact hole is removed. A contact plug and a bit line are formed within the contact hole and the trench.