Semiconductor Fabrication via Selective Etching and Dielectric Protection
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Solution Overview
Problem
At sub-micron dimensions, capacitive coupling between metal interconnects in integrated circuits causes cross talk and RC delay, degrading performance, and existing damascene methods damage low-k dielectric materials during processing.
Innovation Solution
A method involving a chlorine-based etchant to form via openings in a metal oxide layer, followed by a fluorine-based etchant to expose the metal layer while protecting the metal oxide layer with a block layer, minimizing damage to dielectric materials and enabling precise metal interconnection formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If damascene method is used to form metal interconnects, then metal interconnections can be formed, but low-k dielectric materials are damaged during processing
Solution Approach 1:
The patent segments the etching process into multiple distinct steps: first etching through the metal oxide layer to form via openings, then forming a block layer on sidewalls, and finally etching through the block layer and second dielectric layer to expose the metal layer. This segmentation allows selective removal of materials while protecting the low-k dielectric layer from damage.
Solution Approach 2:
The patent applies preliminary action by forming the block layer on the sidewalls of the metal oxide layer before performing the second etching process. This preliminary protective layer prevents the fluorine-based etchant from directly contacting and damaging the low-k dielectric materials during subsequent processing steps.
2Manufacturing precision
If complex dielectric film stack is used in damascene approach, then via/trench lithography and patterning can be performed, but processing complexity increases
Solution Approach 1:
The patent extracts the metal oxide layer as a separate, dedicated component formed on the second dielectric layer. This extracted layer serves as a specialized protective and etching-resistant layer, simplifying the overall process by providing a clear etching pathway without requiring complex multi-layer dielectric stacks with multiple etch stop layers.
Solution Approach 2:
The patent changes the material parameter by introducing a metal oxide layer with distinct etching characteristics (resistance to chlorine-based etchants). This parameter change enables selective etching through the oxide layer while protecting underlying low-k dielectric materials, reducing the need for complex dielectric film stacks.
3Productivity
If sub-micron dimensions are used for metal interconnects, then circuit density increases, but capacitive coupling causes cross talk and RC delay
Solution Approach 1:
The patent introduces the metal oxide layer as an intermediary barrier between adjacent metal interconnect structures. This intermediate layer, combined with the block layer formed on its sidewalls, provides enhanced electrical isolation that reduces capacitive coupling and cross-talk between adjacent interconnects at sub-micron dimensions.
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 reduces damage to dielectric materials and effectively forms metal interconnections with minimal capacitive coupling, enhancing the performance and reliability of integrated circuits by maintaining the integrity of low-k dielectric layers.
Implementation Method 1
performing a first etching process by using a chlorine-based etchant to remove part of the metal oxide layer to forma via opening and expose the second dielectric layer
Implementation Method 2
performing a second etching process by using a fluorine-based etchant to remove part of the block layer and part of the second dielectric layer for exposing a top surface of the metal layer
Data Source
AI summary
A method for fabricating a semiconductor device includes the steps of: providing a first dielectric layer having a metal layer therein; forming a second dielectric layer on the first dielectric layer and the metal layer; forming a metal oxide layer on the second dielectric layer; performing a first etching process by using a chlorine-based etchant to remove part of the metal oxide layer to forma via opening and expose the second dielectric layer; forming a block layer on sidewalls of the metal oxide layer and a top surface of the second dielectric layer; and performing a second etching process by using a fluorine-based etchant to remove part of the block layer and part of the second dielectric layer for exposing a top surface of the metal layer.