Dual-Parameter Atomic Layer Etching for Semiconductor Contact Resistance
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Solution Overview
Problem
Residue left after etching processes in semiconductor device fabrication increases contact resistance due to reduced contact area between interconnects and conductive features, hindering efficient electric current flow.
Innovation Solution
A combination of atomic layer etching (ALE) processes with different operating parameters is employed to minimize residue, where a first ALE process exposes conductive features and a second ALE process removes residual etch stop layer material, optimizing contact area and reducing resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single ALE process is used to etch the opening, then the etching speed is maintained, but residue remains on the conductive features increasing contact resistance
Solution Approach 1:
The patent divides the single ALE process into two distinct ALE processes with different operating parameters. The first ALE process uses a first set of operating parameters to etch the opening through the dielectric layer and etch stop layer, while the second ALE process uses a second set of operating parameters specifically optimized to remove residue from the conductive features. This segmentation allows each process to be optimized for its specific function, resolving the contradiction between maintaining etching speed and reducing contact resistance.
2Manufacturing precision
If ALE process parameters are optimized to remove residue, then contact resistance decreases, but the overall etching efficiency is reduced
Solution Approach 1:
The patent employs periodic action by alternating between two ALE processes with different operating parameters. The first ALE process operates with parameters optimized for rapid material removal to etch through the dielectric and etch stop layers. The second ALE process operates with parameters optimized for residue removal from the conductive features. This periodic alternation between etching and cleaning modes maintains high overall efficiency while ensuring low contact resistance.
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 approach effectively decreases residue, thereby lowering contact resistance between interconnects and conductive features, enhancing the flow of electric current and improving semiconductor device performance.
Implementation Method 1
The etchant species bonds with surface atoms of the material to be etched
Implementation Method 2
A charged ion bombardment is then guided to the etchant layer in order to remove the etchant layer and the atoms bonded to the etchant layer
Data Source
AI summary
A method of fabricating a semiconductor device. The method includes forming source/drain features in a substrate on opposite sides of a gate structure, forming an etch stop layer over the source/drain features, and depositing a dielectric layer on the etch stop layer. The method further includes performing a first atomic layer etching (ALE) process having a first operating parameter value on the dielectric layer to form a first part of an opening, and performing a second ALE process having a second operating parameter value to extend the opening to expose the source/drain features. The first operating parameter value is different from the second operating parameter value.