Recessed Contact Structure for Array Substrate
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Solution Overview
Problem
As the size of elements such as thin film transistors (TFTs) and conductive contacts on array substrates in display devices decreases, the contact resistance between the conductive contacts and the source/drain regions increases, affecting the electrical performance of the array substrate structure.
Innovation Solution
The implementation of a contact structure with a recessed contact opening that exposes a portion of the active layer, allowing for a conductive layer to be conformably formed in the recesses, thereby increasing the physical contact area and reducing contact resistance. This is achieved through a series of etching processes that create recesses in the insulating and inter-layer dielectric layers, allowing the conductive layer to cover more surface area and improve electrical connectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the size of elements such as TFTs and conductive contacts is reduced to improve image resolution, then the image quality and resolution are improved, but the contact resistance between conductive contacts and source/drain regions increases
Solution Approach 1:
The contact structure transitions from a planar contact interface to a three-dimensional recessed structure. The contact opening penetrates through the insulating layer to expose the active layer, creating vertical and lateral contact surfaces. This dimensional change increases the contact area without increasing the planar footprint, thus maintaining low contact resistance while supporting smaller element sizes for higher resolution displays.
Solution Approach 2:
The contact structure embeds the conductive layer within a recessed cavity formed by removing portions of the insulating and inter-layer dielectric layers. This nested configuration allows the conductive layer to be surrounded by dielectric material while maintaining direct contact with the active layer, effectively isolating the contact path while preserving electrical connectivity.
2Productivity
If the size of conductive contacts is reduced, then the element density is improved, but the physical contact area between conductive contacts and source/drain regions decreases
Solution Approach 1:
The contact opening creates a vertical dimension for electrical connection, allowing current to flow through the thickness of the insulating layer rather than requiring a large lateral contact area. The recessed structure provides lateral contact surfaces as well, effectively creating a multi-faceted contact interface that increases total contact area while minimizing planar footprint.
Solution Approach 2:
The contact structure divides the contact interface into multiple surfaces: the bottom surface of the contact opening where the conductive layer contacts the active layer, and the lateral surfaces of the recess where the conductive layer contacts the sidewalls of the insulating layer. This segmentation of the contact interface distributes the electrical connection across multiple surfaces, increasing total contact area without increasing overall contact footprint.
Data Source
AI summary
A contact structure is provided, including a substrate, an active layer, an inter-layer dielectric (ILD) layer, a contact opening, and a conductive layer. The active layer is disposed over the substrate, and the insulating layer is disposed over the active layer; an inter-layer dielectric (ILD) layer over the insulating layer. The contact opening penetrates a portion of the ILD layer and the insulating layer to expose a portion of the active layer, wherein the contact opening includes a first recess portion, and the first recess portion is defined by a bottom surface of the ILD layer, a sidewall of the insulating layer and a top surface of the active layer. The conductive layer is in the contact opening and is electrically connected to the active layer.