Semiconductor Interconnect Air-Gap Structure to Prevent Metal Chamfering
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Solution Overview
Problem
The increase in back-end metal interconnection RC delay in semiconductor structures, such as DRAMs, due to metal chamfering and collapse during etching, and the resulting risk of cracks in the metal layer, which hinders performance improvement.
Innovation Solution
A method involving the formation of a protective layer over a conductive layer, followed by etching to create a trench that penetrates through both layers, allowing for the filling of a dielectric layer with an air gap that extends into the protective layer, thereby reducing chamfering and collapse and increasing air gap height to minimize metal cracks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If low dielectric constant materials are introduced to reduce RC delay, then interconnection performance is improved, but metal chamfering and collapse occur during etching
Solution Approach 1:
A protective layer is introduced as an intermediary between the metal interconnect and the etching process. This protective layer acts as a mediator that prevents direct interaction between the etchant and metal surfaces, thereby eliminating chamfering and collapse while allowing the low dielectric constant material to fulfill its performance function.
Solution Approach 2:
The protective layer is formed in advance before the etching process. This preliminary action prepares the structure to resist subsequent etching damage, preventing metal profile degradation before it can occur during the low dielectric constant material formation process.
2Reliability
If air gaps are formed to reduce parasitic capacitance, then interconnection performance is improved, but the risk of metal cracks increases due to low air gap height
Solution Approach 1:
The protective layer is formed in advance to enable the creation of taller air gaps. This preliminary structural preparation allows the air gap to extend higher without compromising metal integrity, as the protective layer supports the overall structure during and after air gap formation.
Solution Approach 2:
The structure combines multiple materials including the protective layer, metal interconnect, low dielectric constant material, and air gap. This composite structure distributes mechanical stresses and electrical fields across different materials, reducing parasitic capacitance while maintaining metal layer strength through the synergistic combination of components.
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 reduces metal chamfering and collapse, increases air gap height, and enhances the performance of semiconductor structures by minimizing the risk of metal cracks and improving interconnection reliability.
Implementation Method 1
depositing the dielectric material on the surface of the second adhesive layer by a plasma-enhanced chemical vapor deposition process
Data Source
AI summary
The present invention relates to the technical field of semiconductor manufacturing, and in particular, to a method for forming a semiconductor structure and a semiconductor structure. The method for forming a semiconductor structure comprises: forming an interconnect layer and a conductive layer covered on a surface of the interconnect layer; forming a protective layer covering a surface of the conductive layer away from the interconnect layer; forming a trench penetrating the protective layer and the conductive layer; and filling a dielectric layer in the trench, and forming an air gap in the dielectric layer, the air gap extending from the trench in the conductive layer into the trench in the protective layer.