Manganese Cap Layer for Air Gap Formation in Nanocopper Interconnects
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Solution Overview
Problem
Current air gap formation processes in integrated circuits lead to significant copper erosion, posing reliability issues due to increased capacitance between interconnects, which limits device speed and increases power consumption.
Innovation Solution
A manganese-containing cap layer is formed over interconnects in an interlevel dielectric layer, acting as a temporary protection layer to prevent erosion during air gap formation by damaging and removing a portion of the interlevel dielectric layer between interconnects, followed by sealing with a dielectric cap layer to create openings and air gaps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If air gap formation process is performed to reduce interconnect capacitance, then power consumption is reduced, but copper interconnect erosion occurs leading to reliability issues
Solution Approach 1:
A manganese-containing cap layer is deposited over the copper interconnects to serve as an intermediary protective layer during the air gap formation process. This cap layer acts as a mediator that protects the copper interconnects from erosion by the etching chemicals and plasma, while still allowing the air gap to be formed in the dielectric material between the interconnects. The manganese cap layer is subsequently removed after serving its protective function.
Solution Approach 2:
The manganese-containing cap layer is deposited in advance before the air gap formation process to pre-protect the copper interconnects. This preliminary protective action ensures that the interconnects are shielded from erosion before the damaging etching process begins, maintaining their integrity throughout the air gap formation.
2Speed
If air gap formation process is performed to reduce capacitive coupling, then device speed is improved, but interconnect erosion occurs
Solution Approach 1:
The manganese-containing cap layer serves as a protective intermediary that enables the air gap formation process to proceed without eroding the copper interconnects. By having this protective layer in place, the device can achieve the speed improvements from reduced capacitive coupling while the interconnect integrity is maintained throughout the process.
3Reliability
If manganese-containing cap layer is formed and removed to prevent erosion, then interconnect integrity is maintained, but process complexity increases
Solution Approach 1:
The manganese-containing cap layer is used as a temporary sacrificial protective layer that is deposited, serves its protective function during air gap formation, and then selectively removed. This approach of using a removable protective layer maintains interconnect integrity while the additional process steps are temporary and controlled.
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
The method effectively prevents interconnect erosion during air gap formation, reducing capacitive coupling and power consumption while maintaining the integrity of the semiconductor structure.
Implementation Method 1
The Mn-containing cap layer acts as a temporary protection layer preventing erosion of the underlying interconnects during the air gap formation process
Implementation Method 2
The dielectric cap layer seals the air gap between the adjacent interconnects in the first subset of the plurality of interconnects
Data Source
AI summary
After forming a manganese (Mn)-containing cap layer over interconnects embedded in an interlevel dielectric (ILD) layer, a lithographic stack is formed over the Mn-containing cap layer. The lithographic stack is subsequently patterned to expose a portion of the Mn-containing cap layer that overlies a subset of the interconnects between which the air gaps are to be formed. A portion of the ILD layer located between the subset of the interconnects is damaged through the exposed portion of the Mn-containing cap layer. The damaged portion of the ILD layer is subsequently removed to form openings between the subset of the interconnects. The Mn-containing cap layer acts as a temporary protection layer preventing erosion of the underlying interconnects during the air gap formation.