Semiconductor Metal Lines with Extrusion Prevention Film
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Solution Overview
Problem
Semiconductor devices face issues with hillock and extrusion formation during annealing processes, leading to reliability and yield concerns due to stress relief mechanisms in metal wiring, where extrusions can short neighboring lines.
Innovation Solution
A method involving a layered structure of metal materials with a constraining layer and an extrusion prevention film layer, such as Low Temperature Oxide (LTO) or PECVD oxide/nitride, applied post-patterning to prevent extrusion of aluminum during annealing, thereby reducing stress-induced defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a constraining layer is used on top of the metal level to suppress hillock formation, then hillock formation is reduced, but extrusion formation occurs instead
Solution Approach 1:
The solution divides the single constraining layer into two separate layers: a lower constraining layer that suppresses hillock formation, and an upper extrusion prevention layer that prevents extrusion. This segmentation allows each layer to specialize in preventing one specific type of defect without causing the other defect.
2Stability of the object's composition
If the metal layer is allowed to expand during annealing, then stress relief occurs via hillock formation, but extrusions form and can short neighboring lines
Solution Approach 1:
The upper extrusion prevention layer acts as an intermediary between the metal layer and the external environment. It allows the metal to relieve stress through controlled mechanisms while preventing the harmful extrusion from reaching the surface and causing shorts between neighboring lines.
3Stability of the object's composition
If the temperature increase magnitude and duration are increased during annealing, then stress relief is enhanced, but extrusion size increases
Solution Approach 1:
The extrusion prevention layer is applied before the annealing process. This preliminary action prepares the structure in advance to handle the stress relief that will occur during annealing, allowing the metal to expand and relieve stress without forming harmful extrusions, even when temperature increase magnitude and duration are optimized for stress relief.
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
Significantly reduces the formation of aluminum extrusions and hillocks, enhancing the reliability and yield of semiconductor devices by preventing shorting and voiding issues, as demonstrated by experimental data showing a substantial decrease in defects with optimal film layer thickness.
Implementation Method 1
stresses can build up in the aluminum or other metal layer during annealing processes
Implementation Method 2
during the annealing process, stress in the metal line can be relieved
Implementation Method 3
the grain pushes up to relieve the compressive stress
Implementation Method 4
forming an extrusion prevention film layer on the at least one metal structure
Data Source
AI summary
Disclosed are semiconductor structures with metal lines and methods of manufacture which reduce or eliminate extrusion formation. The method includes forming a metal wiring comprising a layered structure of metal materials with an upper constraining layer. The method further includes forming a film on the metal wiring which prevents metal extrusion during an annealing process.