Semiconductor Contact Recess via Sacrifice Layer for Bridge Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
As semiconductor devices integrate more densely, the reduced pitch of interconnections leads to a decreased alignment margin between bit lines and contacts, causing bridges to form between adjacent interconnections during the damascene process, which affects the quality and reliability of the semiconductor device.
Innovation Solution
A method involving the formation of a sacrifice layer over the interlayer dielectric layer, selective etching to create trenches, burying non-dry-etchable conductive material within these trenches, and subsequent removal of the sacrifice layer to form recesses in the conductive contacts, preventing bridges and reducing coupling capacitance by increasing the distance between interconnections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the pitch of interconnections is reduced to increase integration degree, then productivity and device density are improved, but alignment margin decreases and bridge defects occur
Solution Approach 1:
The patent applies preliminary action by forming a sacrifice layer before the conductive interconnection layer. This sacrifice layer is selectively removed to create recesses in the conductive contact, which increases the distance to adjacent interconnections and prevents bridge formation. The preliminary structure modification enables higher integration without sacrificing alignment margin.
Solution Approach 2:
The patent applies local quality by creating non-uniform structures in the conductive contact. Specifically, recesses are formed only in specific regions where adjacent interconnections are located, while other regions maintain their original height. This localized modification increases distance precisely where needed to prevent bridges, while maintaining optimal electrical contact elsewhere.
2Area of stationary object
If the distance between conductive contact and adjacent interconnection is reduced, then area is reduced and integration is improved, but bridge formation occurs between contact and interconnection
Solution Approach 1:
The sacrifice layer is formed and selectively removed in advance to create recesses that prevent bridge formation. This preliminary structural preparation allows the conductive interconnection to be formed closer to the conductive contact without risking bridge defects, thereby reducing overall device area while maintaining reliability.
Solution Approach 2:
The sacrifice layer acts as an intermediary structure that is temporarily present during fabrication. Its selective removal creates the necessary recesses that serve as a protective feature, preventing direct contact (bridge formation) between the conductive contact and adjacent interconnection while allowing minimal spacing.
3Reliability
If conductive material that cannot be dry-etched is used for interconnection, then electrical resistance is reduced, but the material cannot be directly patterned and requires damascene process
Solution Approach 1:
The sacrifice layer is formed and selectively removed before forming the conductive interconnection. This preliminary action creates recesses that define the final shape and position of the conductive interconnection, eliminating the need for complex damascene process steps while still allowing the use of low-resistance materials like copper that cannot be dry-etched.
Solution Approach 2:
The sacrifice layer is extracted (removed) after serving its purpose as a temporary structure. Its removal leaves behind the desired recesses in the conductive contact, which enable precise positioning of the conductive interconnection without requiring the conductive material itself to be etched or patterned.
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 effectively prevents bridge formation between conductive contacts and interconnections, reduces coupling capacitance, and enhances the overall characteristics of the semiconductor device by increasing the distance between adjacent interconnections and minimizing interference.
Implementation Method 1
selectively etching the sacrifice layer to form a trench exposing the conductive contact
Implementation Method 2
forming a conductive interconnection by burying a conductive material that may not be dry-etched, in the trench
Implementation Method 3
removing the sacrifice layer; and forming a recess by dry-etching a part of the conductive contact exposed after the removing of the sacrifice layer
Data Source
AI summary
A method for fabricating a semiconductor device includes forming a first interlayer dielectric layer having a conductive contact, forming a sacrifice layer having a conductive interconnection over the first interlayer dielectric layer such that the conductive interconnection is contacted with the conductive contact, removing the sacrifice layer, and forming a recess by removing a part of the conductive contact exposed by the conductive interconnection.