Semiconductor Contact Plug Alignment via Sacrificial Layer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The miniaturization of semiconductor devices leads to alignment issues during contact plug fabrication, causing short circuits between gates and sources/drain, which can result in device failure or failure of the entire integrated circuit.
Innovation Solution
A method involving the formation of a patterned sacrificial layer on a substrate with transistors, followed by etching and replacement to create contact holes with a larger process window, thereby preventing misalignment-induced short circuits by forming contact holes that correspond to the sources/drains, ensuring accurate electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional contact plug fabrication is used, then manufacturing simplicity is maintained, but alignment precision deteriorates causing contact plug shift and short circuits
Solution Approach 1:
A sacrificial layer is introduced as an intermediary element between the gate and the contact hole formation process. The sacrificial layer is patterned to define the contact hole positions, and after the contact holes are formed, the sacrificial layer is removed. This intermediary approach enables precise contact plug alignment without directly aligning to the gate, thus improving manufacturing precision while managing process complexity.
Solution Approach 2:
The sacrificial layer is formed and patterned in advance before the contact hole etching process. This preliminary action establishes the precise contact hole positions beforehand, ensuring accurate alignment with the sources/drains. By performing the alignment-critical step beforehand, the method improves contact plug alignment precision without complicating the overall fabrication process.
2Area of moving object
If feature size is reduced for miniaturization, then device density is improved, but alignment tolerance deteriorates causing short circuits
Solution Approach 1:
The sacrificial layer serves as a mediator that decouples the alignment requirement from the miniaturized feature dimensions. By using the sacrificial layer pattern as the alignment reference instead of directly aligning to the miniaturized gate or source/drain, the method maintains manufacturing precision even as feature sizes are reduced for higher device density.
3Reliability
If direct contact hole formation is used, then process steps are minimized, but short circuit risk increases due to misalignment
Solution Approach 1:
The sacrificial layer is used as a temporary intermediary structure that enables reliable contact hole formation. The process steps involving the sacrificial layer (formation, patterning, and removal) are justified by the significant improvement in device reliability they provide through precise alignment and prevention of short circuits between gates and sources/drains.
Solution Approach 2:
The sacrificial layer is formed, used for defining contact hole positions, and then removed after serving its purpose. This temporary structure is discarded after enabling precise contact hole formation, improving device reliability without permanently increasing complexity. The sacrificial layer is recovered (removed) after fulfilling its alignment function.
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 method effectively avoids short circuits between gates and sources/drains, enhancing the reliability of semiconductor devices by providing a larger process window for contact plug formation and allowing for flexible integration before or after the replacement metal gate process.
Implementation Method 1
an etching process is performed to etch the first dielectric layer through the second openings to form a plurality of first contact holes exposing the sources/drains of the transistors
Data Source
AI summary
A method for manufacturing contact plugs for semiconductor devices includes the following steps. A substrate is provided. The substrate includes a plurality of transistor and a first dielectric layer filling spaces between the transistors formed thereon. The transistors respectively include a gate and a source/drain. A patterned sacrificial layer is formed on the first dielectric layer. The patterned sacrificial layer includes a plurality of first openings corresponding to the gates of the transistors. A second dielectric layer filling up the first openings in the patterned sacrificial layer is formed and followed by removing the sacrificial layer to form a plurality of second openings in the second dielectric layer. The second openings are formed correspondingly to the sources/drains of the transistors. An etching process is performed to etch the first dielectric layer through the second openings to form a plurality of first contact holes exposing the sources/drains of the transistors.