Deep Trench Capacitor Air-Gap Structure for Wafer Warpage Relief
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Solution Overview
Problem
Deep trench capacitors face challenges with substrate warpage and cracking due to thermal expansion of electrodes and dielectric layers, especially as chip thickness decreases, compromising the rigidity and robustness of semiconductor wafers.
Innovation Solution
Incorporating air gaps within each trench of the capacitor structure, enclosed by capacitor electrode and dielectric layers, to mitigate thermal stress and increase capacitance density while reducing substrate warpage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If deep trench capacitors are designed with high aspect ratio to achieve high density layout, then capacitance density is improved, but substrate warpage and cracking increase due to thermal expansion stress
Solution Approach 1:
The capacitor structure is segmented into multiple horizontal layers (first capacitor, second capacitor, third capacitor) stacked vertically within the trench. This segmentation allows each layer to independently manage thermal expansion stress while collectively achieving high capacitance density, resolving the contradiction between high density and substrate integrity
Solution Approach 2:
Multiple capacitor structures are nested within a single trench, with each capacitor layer containing electrodes and dielectric materials arranged concentrically. This nesting approach maximizes the use of vertical space for capacitance while the shared trench structure provides unified mechanical support to reduce substrate warpage
2Length of moving object
If chip thickness is reduced to achieve thinner chips, then device integration is improved, but wafer rigidity and robustness decrease making it more vulnerable to damage
Solution Approach 1:
The capacitor structure employs composite materials including conductive materials for electrodes, dielectric materials for insulation, and optional protective coating materials. This composite approach creates a multi-functional structure that maintains mechanical strength despite reduced chip thickness while enabling high capacitance density
Solution Approach 2:
The invention transitions from planar capacitor layouts to vertical three-dimensional structures with high aspect ratio trenches. By utilizing the vertical dimension, the design achieves high capacitance density without increasing surface area, and the deep trench structure provides inherent mechanical reinforcement to maintain wafer rigidity in thinner chips
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
The air gaps allow thermal expansion of capacitor layers without applying excessive force on the substrate, thereby reducing substrate warpage and cracking, while increasing the number of trenches and overall capacitance density.
Implementation Method 1
The air gaps allow thermal expansion of capacitor layers without applying excessive force on the substrate
Data Source
AI summary
Various embodiments of the present disclosure provide a semiconductor device structure. The semiconductor device structure comprises a substrate comprising a first trench, wherein the first trench extends into a front side surface of the substrate, a first trench capacitor comprising a plurality of first capacitor electrode layers and a plurality of first capacitor dielectric layers disposed in alternating manner within the first trench and over the front side surface of the substrate, wherein a first air gap is enclosed by the plurality of first capacitor electrode layers and the plurality of first capacitor dielectric layers within the first trench, an interconnect structure disposed over the first trench capacitor, wherein one or more first capacitor electrode layers of the plurality of first capacitor electrode layers are in electrical connection with a first conductive feature in a dielectric layer of the interconnect structure, and a first seal ring structure disposed in the interconnect structure and encircling an interior portion of the substrate, wherein at least a portion of the first seal ring structure is in contact with the first conductive feature.