Semiconductor Contact Isolation Structure for Short-Circuit Risk
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Solution Overview
Problem
As semiconductor devices evolve with smaller dimensions and increased density, the proximity of conductive contacts in integrated circuits poses a risk of short circuits, necessitating an improved semiconductor device structure and manufacturing method to prevent such failures.
Innovation Solution
The method involves forming a semiconductor device structure with fins and sacrificial gate stacks, followed by the deposition of spacers, recessing of semiconductor layers, and replacement gate structures, along with the use of treated and untreated hard mask layers to minimize parasitic capacitance and prevent short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the dimensions of features in the front-end-of-line (FEOL) are reduced to increase device density, then the density of elements increases, but conductive contacts in the middle-of-line (MOL) and metal gate may get too close to create a short circuit
Solution Approach 1:
The patent introduces a multi-layer three-dimensional structure with vertical stacking of conductive contacts, interlayer dielectric layers, and metal gates. This vertical dimensionality allows horizontal spacing to be reduced while maintaining electrical isolation through vertical separation, thus increasing device density without creating short circuits between adjacent contacts
Solution Approach 2:
The patent employs interlayer dielectric layers as intermediary materials positioned between conductive contacts and around metal gates. These dielectric layers act as insulating barriers that prevent short circuits while allowing the conductive elements to be placed in close proximity, enabling higher device density with maintained reliability
2Length of moving object
If the spacing between conductive contacts and metal gates is reduced to increase device density, then element density increases, but the risk of short circuits increases
Solution Approach 1:
The patent transitions from two-dimensional planar spacing to three-dimensional vertical stacking, where conductive contacts are positioned at different vertical levels separated by interlayer dielectric layers. This allows horizontal spacing to be minimized while vertical isolation prevents short circuits, achieving reduced spacing without compromising reliability
Solution Approach 2:
The patent uses composite structures combining conductive materials (for contacts and gates) with insulating dielectric materials (for isolation layers). This composite approach enables close spacing of conductive elements while the dielectric components provide the necessary electrical isolation to prevent short circuits
3Manufacturing precision
If photolithography capabilities are improved to define smaller structures, then feature dimensions are reduced, but new limiting factors emerge in MOL and metal gate positioning
Solution Approach 1:
The patent divides the semiconductor structure into multiple discrete layers including FEOL structures, interlayer dielectric layers, conductive contacts, and metal gates. Each layer can be independently formed and controlled using photolithography, allowing precise dimension control while managing complexity through modular layer-by-layer fabrication
Solution Approach 2:
The patent employs vertical layering to separate functions that would otherwise require close horizontal proximity. This vertical segmentation allows each layer to be optimized and controlled independently by photolithography, reducing the interdependence between features and managing device complexity while achieving small dimensions
Data Source
AI summary
A semiconductor device structure, along with methods of forming such, are described. The semiconductor device structure includes a gate electrode layer disposed over a substrate, a source/drain epitaxial feature disposed over the substrate, a first hard mask layer disposed over the gate electrode layer, and a contact etch stop layer (CESL) disposed over the source/drain epitaxial feature. The structure further includes a first interlayer dielectric (ILD) layer disposed on the CESL and a first treated portion of a second hard mask layer disposed on the CESL and the first ILD layer. A top surface of the first hard mask layer and a top surface of the first treated portion of the second mask layer are substantially coplanar. The structure further includes an etch stop layer disposed on the first hard mask layer and the first treated portion of the second mask layer.