CMP Process with Fibrous Pad for Protrusion Removal
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Solution Overview
Problem
Conventional CMP processes fail to remove protrusions at the corners of holes or trenches without significantly altering the depth and profile, leading to incomplete filling and material voids during subsequent processes.
Innovation Solution
A chemical mechanical polishing process using a polishing pad with fibers and an abrasive-free slurry, where the fibers intermittently contact the protrusion perpendicular to the surface, allowing for precise removal of protrusions without damaging the substrate or altering the profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an anisotropic etching process is performed to remove the protrusion by ion bombardment, then the protrusion at the corner of the top of the hole is removed, but the material at and around the corner is greatly removed simultaneously, causing the profile of the hole to be greatly changed
Solution Approach 1:
The polishing pad is segmented into multiple fibers with different lengths, where longer fibers selectively contact and remove the protrusion while shorter fibers protect the surrounding area. This segmentation allows precise control over which material is removed, eliminating the need for anisotropic etching that causes excessive material removal.
Solution Approach 2:
The polishing pad has non-uniform fiber length distribution creating different polishing aggressiveness in different locations. The longer fibers at the leading edge provide aggressive protrusion removal, while shorter fibers toward the trailing edge provide gentler polishing, creating a gradient that preserves the hole profile while removing the protrusion.
2Manufacturing precision
If an anisotropic etching process is performed to remove the protrusion, then the protrusion is removed, but the substrate exposed from the hole is partially removed simultaneously, changing the depth and profile of the hole
Solution Approach 1:
The polishing process is made dynamic through the relative motion between the polishing pad and the substrate, combined with the intermittent contact of fibers with the protrusion. This dynamic approach allows selective removal of the protrusion during specific phases of the polishing cycle, preventing excessive removal of the substrate and preserving the original hole depth.
Solution Approach 2:
The fiber length distribution and polishing pressure are optimized to change the effective polishing parameters. By controlling these parameters, the process achieves high protrusion removal efficiency while limiting substrate removal, thereby maintaining the original hole depth and profile.
3Manufacturing precision
If conventional CMP process is used, then the protrusion can be removed, but the thickness of the layer is greatly reduced and the depth and profile of the hole are changed
Solution Approach 1:
The polishing pad utilizes a porous structure with controlled void spaces that allow slurry penetration and facilitate selective material removal. The porosity enables the pad to conform to the surface topology, allowing fibers to reach into and remove protrusions without requiring excessive polishing that would reduce the overall layer thickness.
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
Effectively removes protrusions without reducing the layer thickness or changing the depth and profile of the holes or trenches, ensuring complete filling and maintaining structural integrity.
Implementation Method 1
the plurality of fibers of the polishing pad are intermittently contacted with the protrusion in the presence of an abrasive-free slurry
Data Source
AI summary
Provided is a chemical mechanical polishing process. The process includes the following steps: a layer to be polished is provided, wherein the layer to be polished has a hole, a trench and/or an opening formed therein, and a protrusion is formed at the corner of the top of the hole, the trench and/or the opening; a polishing pad with a plurality of fibers on the surface thereof is provided; and in a moving direction perpendicular to the top surface of the layer to be polished, the plurality of fibers of the polishing pad are intermittently contacted with the protrusion in the presence of an abrasive-free slurry.