Recessed Storage Node Contact Plug for Capacitor Fabrication
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Solution Overview
Problem
As semiconductor devices integrate more densely, the small size of capacitor bottoms limits contact resistance reduction, and residual barrier metals can cause bridges between capacitors during the etching process.
Innovation Solution
A method involving a recessed storage node contact plug with a sloped profile and localized barrier metal deposition to increase contact area, reduce contact resistance, and prevent residue-induced bridges, while maintaining structural integrity during the dip-out process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the bottom size of capacitor is decreased to increase integration scale, then the area utilization is improved, but the contact area with bottom storage node contact plug decreases resulting in increased contact resistance
Solution Approach 1:
The contact plug is transformed from a flat bottom structure to a sloped profile structure, changing the geometric dimension from 2D to 3D. This sloped profile increases the contact surface area between the contact plug and the bottom electrode, thereby reducing contact resistance while maintaining the same planar footprint area for higher integration density.
2Reliability
If barrier metal is deposited to reduce contact resistance and improve adhesion, then the electrical contact is improved, but residues of barrier metal remain after etching process causing bridges between capacitors
Solution Approach 1:
The barrier metal is selectively deposited only in specific locations: on the sloped profile of the contact plug and in the opening where the bottom electrode will be formed. This localized deposition ensures adequate barrier metal for electrical contact while avoiding excessive metal in areas where it would create harmful residues and bridges between adjacent capacitors.
3Stability of the object's composition
If a supporting layer is formed to prevent collapse of bottom electrode during dip out process, then the structural stability is improved, but more bridges occur between capacitors due to barrier metal residues
Solution Approach 1:
The barrier metal is deposited in advance on the sloped contact plug profile before the etching and dip-out processes. This preliminary localized deposition provides the necessary adhesion and structural support for the bottom electrode during subsequent processing steps, while the controlled deposition pattern prevents residue formation that would cause bridges.
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 effectively reduces contact resistance, secures capacitance without height increase, and prevents bridge formation between capacitors by enhancing adhesion and structural support.
Implementation Method 1
recessing the storage node contact plug to a certain depth to obtain a sloped profile
Implementation Method 2
forming a barrier metal over the surface profile of the recessed storage node contact plug
Data Source
AI summary
A method for fabricating a capacitor in a semiconductor device includes forming an insulation layer over a substrate, forming a storage node contact plug passing through the insulation layer and coupled to the substrate, recessing the storage node contact plug to a certain depth to obtain a sloped profile, forming a barrier metal over the surface profile of the recessed storage node contact plug, forming a sacrificial layer over the substrate structure, etching the sacrificial layer to form an opening exposing the barrier metal, forming a bottom electrode over the surface profile of the opening, and removing the etched sacrificial layer.