Metal Liner Overhang Reduction in Semiconductor Trenches
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Solution Overview
Problem
The challenge in semiconductor manufacturing is filling small openings or trenches with conductive materials due to overhang issues during the fabrication process, leading to voids and increased contact resistance in conductive features.
Innovation Solution
An etching process using a halide of the metal in the seed or liner layer is employed to remove or reduce overhangs, allowing for the complete filling of openings with conductive layers without voids by forming a self-limiting etching process that reacts with the metal without affecting the underlying or oxidized layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conductive materials are deposited to fill small openings or trenches, then the openings can be filled with conductive features, but overhang issues occur leading to voids and increased contact resistance
Solution Approach 1:
An etching process is performed before the conductive material deposition to remove overhangs from the opening walls. This preliminary action prevents the overhangs from interfering with subsequent complete filling, eliminating void formation and ensuring reliable electrical connections.
Solution Approach 2:
The harmful overhang structures are selectively removed from the opening walls before filling. By extracting these problematic features that would otherwise prevent complete filling, the process enables void-free conductive feature formation and maintains electrical connection reliability.
2Productivity
If feature sizes are scaled down to increase functional density, then production efficiency increases and costs decrease, but filling small openings becomes more difficult
Solution Approach 1:
The etching step is introduced as a preliminary process before deposition to prepare the opening walls by removing overhangs. This enables successful filling of scaled-down features while maintaining high production efficiency, as the additional step is simple and does not significantly increase process complexity.
Solution Approach 2:
The process introduces a new parameter (etching treatment) that changes the surface morphology of the opening walls. By modifying the wall profile to remove overhangs, the filling process becomes feasible even for very small scaled-down features, maintaining ease of manufacture despite size reduction.
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 ensures reliable electrical connections by eliminating voids in conductive features, reducing resistance, and improving the reliability of semiconductor devices by ensuring the conductive layers fill the openings without gaps.
Implementation Method 1
An etching process using a halide of the metal in the seed or liner layer is employed to remove or reduce overhangs
Data Source
AI summary
Overhang reduction methods are disclosed. In some embodiments, a method includes forming a recess in a dielectric layer, the recess defining first sidewalls of the dielectric layer. The method also includes depositing a first conductive layer over an upper surface of the dielectric layer and the sidewalls of the dielectric layer, the first conductive layer having a first overhang, removing the first overhang of the first conductive layer using an etchant selected from the group consisting of a halide of the first conductive layer, Cl2, BCl3, SPM, SC1, SC2, and combinations thereof, and filling the recess with a second conductive layer.