Nested Contact Structure for Semiconductor Fabrication Margin
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Solution Overview
Problem
As semiconductor devices become highly integrated, challenges arise in forming stable contacts due to reduced channel lengths, increased alignment errors, and parasitic capacitance, leading to higher contact resistance, reduced fabrication margins, and increased risk of electrical shorts, especially in 6 F2-structured cell regions where spacing between elements is minimal.
Innovation Solution
A method involving the formation of a buried word line orthogonal to the active region, followed by insulation film patterning, and the creation of line patterns for storage node contacts, which are then isolated to form island patterns, along with the formation of bit line contacts with spacers to prevent electrical shorts and increase fabrication margins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the contact size is reduced to increase integration degree, then the integration degree is improved, but the contact resistance is increased
Solution Approach 1:
The patent implements a multi-layer nested contact structure where a first contact extends from the surface to a first depth, a second contact extends from the first depth to a second depth, and a third contact extends from the second depth to a third depth. This nested arrangement increases the total contact area with the active region without increasing the surface footprint, thereby reducing contact resistance while maintaining high integration density.
Solution Approach 2:
The patent transitions from a two-dimensional contact area to a three-dimensional contact volume by creating contacts at multiple depth levels. The vertical dimension is utilized to create overlapping contact regions that extend through different depths of the substrate, effectively increasing the contact area without expanding the lateral dimensions.
2Productivity
If the spacing between neighboring constituent elements is reduced to increase integration, then the integration degree is improved, but the electrical insulation between elements becomes difficult
Solution Approach 1:
The insulation film is formed as a nested structure that coats the sidewalls of contacts at multiple depth levels. The insulation film patterns create isolated regions that prevent electrical interference between neighboring contacts, even when the lateral spacing is reduced for higher integration.
Solution Approach 2:
The insulation film is selectively formed at specific locations where electrical isolation is needed, such as on the sidewalls of contacts and in regions between neighboring elements. This localized insulation approach provides electrical isolation precisely where required without unnecessarily increasing the overall device footprint.
3Productivity
If the channel length is shortened to increase integration, then the integration degree is improved, but the short channel effect such as punch-through occurs
Solution Approach 1:
The multi-level nested contact structure increases the effective contact area with the active region, improving the electrical connection without requiring an increase in channel length. This allows the channel to remain short for high integration while maintaining reliable electrical contact through the vertically stacked contact regions.
Data Source
AI summary
A method for manufacturing a semiconductor device is disclosed. A method for manufacturing a semiconductor device includes forming a device isolation structure for defining an active region, forming a buried word line traversing the active region, forming one or more insulation film patterns over the buried word line, forming a line pattern including a first conductive material at a position between the insulation film patterns, and forming a plurality of storage node contacts (SNCs) by isolating the line pattern. As a result, when forming a bit line contact and a storage node contact, a fabrication margin is increased.