Semiconductor Sinker Contacts Using Diffusion Confining Structures
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Solution Overview
Problem
Conventional sinker contacts in semiconductor devices are large due to lateral diffusion, requiring significant real estate and limiting the scalability of semiconductor devices, as they need to be wide enough to reach deep buried layers effectively.
Innovation Solution
The implementation of a diffusion confining structure within an isolation ring structure that confines the diffusion of dopant elements, allowing for smaller sinker contacts by defining their edges and ensuring electrical contact to buried layers without excessive lateral spread.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional sinker contacts are formed by implanting dopants and annealing to drive dopants deeper into the substrate, then electrical contact to buried layers is achieved, but the lateral diffusion width becomes on the order of the vertical diffusion depth, resulting in large contact sizes of tens of μm or greater
Solution Approach 1:
The patent divides the contact formation process into two distinct stages: first forming a small implant region, then using a diffusion confining structure to guide subsequent dopant diffusion. This segmentation allows the implant area to be small while the diffusion path is controlled, resolving the contradiction between achieving deep electrical contact and maintaining small contact size.
Solution Approach 2:
The diffusion confining structure acts as an intermediary element that mediates between the dopant source and the buried layer. This structure confines the dopant diffusion path, ensuring that dopants travel vertically to reach the buried layer without spreading laterally, thus enabling small contact size while maintaining reliable electrical contact.
2Reliability
If sinker contacts are made large to ensure adequate dopant diffusion to deep buried layers, then electrical contact reliability is improved, but the real estate required on the IC increases, limiting device scaling
Solution Approach 1:
The patent transitions from relying on lateral diffusion to utilizing vertical diffusion by introducing the diffusion confining structure. This dimensional change in the diffusion path allows dopants to reach deep buried layers through vertical transport rather than lateral spread, enabling small contact footprints while maintaining contact reliability and supporting device scaling.
Solution Approach 2:
The patent changes the diffusion parameters by introducing a diffusion confining structure that alters the diffusion geometry from lateral to vertical. This parameter change in the diffusion path direction enables achieving the same electrical contact reliability with significantly reduced contact dimensions, thereby supporting continued device scaling.
3Area of moving object
If the lateral diffusion width is reduced to enable smaller sinker contacts, then the surface area required is reduced, but it becomes difficult to achieve adequate dopant penetration to deep buried layers
Solution Approach 1:
The diffusion confining structure serves as an intermediary that decouples the relationship between lateral diffusion width and vertical diffusion depth. By confining dopants within this structure, the patent enables small surface area contacts while maintaining precise control over dopant penetration depth to buried layers, resolving the manufacturing precision challenge.
Solution Approach 2:
The patent applies local quality by creating a specific region with controlled diffusion properties through the diffusion confining structure. This localized control allows dopant diffusion to be restricted in the lateral direction while promoted in the vertical direction, enabling small contact area with adequate dopant penetration depth.
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 enables the formation of smaller sinker contacts with reduced surface area requirements, allowing for more compact semiconductor device designs and improved scalability by controlling the diffusion of dopant elements within the semiconductor device.
Implementation Method 1
at least one dopant element implanted and diffused into the top portion of the workpiece
Implementation Method 2
annealing or heating the substrate to drive the dopants deeper into the substrate
Data Source
AI summary
Semiconductor devices and methods of manufacture thereof are disclosed. In a preferred embodiment, a semiconductor device includes a workpiece having a buried layer disposed beneath a top portion of the workpiece. An isolation ring structure is disposed within the top portion of the workpiece extending completely through at least a portion of the buried layer, the isolation ring structure comprising a ring having an interior region. A diffusion confining structure is disposed within the interior region of the isolation ring structure. A conductive region is disposed within the top portion of the workpiece within a portion of the interior of the isolation ring structure, the conductive region comprising at least one dopant element implanted and diffused into the top portion of the workpiece. The diffusion confining structure defines at least one edge of the conductive region, and the conductive region is coupled to the buried layer.