Semiconductor Contact Plug Asymmetric Cross-Section
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Solution Overview
Problem
Existing semiconductor devices face challenges in forming reliable contact plugs in small regions, particularly in achieving excellent electrical contact between active regions and other structures, with existing self-aligning contact methods often resulting in higher resistance and more defects.
Innovation Solution
A semiconductor device design featuring a first and second contact plug on a semiconductor layer, with a conductive layer electrically connected to the first plug and insulated from the second plug by a sidewall insulating layer, where the second plug has a larger lower portion cross-sectional area than its upper portion, and the insulating layer is positioned to face both the side and bottom surfaces of the conductive layer, using materials like polysilicon, aluminum, and other metals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional self-aligning contact methods are used to form contact plugs in small regions, then the manufacturing process is simplified, but the electrical contact quality deteriorates with higher resistance and more defects
Solution Approach 1:
The contact plug formation process is segmented into multiple stages: first forming the bit line contact plug, then using its spacer as a mask to form the storage contact plug. This segmentation allows each contact plug to be optimized independently while maintaining the self-aligning advantage, thereby improving electrical contact quality without sacrificing manufacturing simplicity.
Solution Approach 2:
The spacer is formed preliminarily on the bit line contact plug before the storage contact plug is created. This preliminary spacer structure serves as a pre-positioned mask that ensures precise alignment for the storage contact plug, enabling high-quality electrical contact while maintaining process simplicity.
2Area of moving object
If the contact plug size is reduced to fit small regions, then the device integration is improved, but the electrical contact area is reduced leading to higher resistance
Solution Approach 1:
The contact plug structure transitions from a single-dimensional small footprint to a multi-dimensional configuration with varying cross-sectional areas. The lower portion has a larger cross-sectional area than the upper portion, creating a tapered shape that increases the electrical contact area with the active region while maintaining a compact overall footprint suitable for small device regions.
3Reliability
If the contact plug cross-sectional area is increased to reduce resistance, then the electrical contact quality is improved, but the device area occupied is increased
Solution Approach 1:
The contact plug employs an asymmetric cross-sectional area distribution along its height, with the lower portion having a larger area than the upper portion. This asymmetric design concentrates the increased contact area at the critical interface with the active region where it is most needed for reducing resistance, while the upper portion remains compact to minimize the overall device area occupation.
Data Source
AI summary
A semiconductor device and associated methods, the semiconductor device including a semiconductor layer including a first region and a second region, a first contact plug disposed on the semiconductor layer and electrically connected to the first region, a second contact plug disposed on the semiconductor layer and electrically connected to the second region, a conductive layer electrically connected to the first contact plug, the conductive layer having a side surface and a bottom surface, and an insulating layer disposed between the conductive layer and the second contact plug so as to insulate the conductive layer from the second contact plug, the insulating layer facing the side surface and a portion of the bottom surface of the conductive layer.