Semiconductor Wiring Structure With Dummy Pillars for CMP Flatness
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Solution Overview
Problem
Chemical Mechanical Polishing (CMP) processes result in uneven top surfaces of conductive structures due to differing removal rates of metal and dielectric materials, leading to erosion and curvature issues in semiconductor devices.
Innovation Solution
Incorporation of dummy pillars made of dielectric material within the conductive structure to reduce pattern density, ensuring the conductive structure remains flatter after CMP processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If CMP process is used to planarize the surface, then surface flatness is improved, but top surface erosion of conductive structure occurs due to uneven removal rates
Solution Approach 1:
The patent introduces dummy pillars (local dielectric structures) within the conductive structure to create non-uniform pattern density distribution. This local modification causes the CMP process to remove dielectric material at different rates in different regions, compensating for the erosion that would otherwise occur on the conductive structure surface. The dummy pillars are strategically placed to achieve the desired pattern density adjustment in specific areas.
Solution Approach 2:
The dummy pillars are formed in advance before the CMP process to pre-compensate for the erosion that will occur during CMP. By adjusting the pattern density through dummy pillars beforehand, the patent creates a counterbalancing effect that prevents the harmful erosion of the conductive structure surface during the subsequent CMP process.
2Reliability
If pattern density is increased to improve conductivity, then electrical performance is improved, but CMP erosion is worsened due to higher metal content
Solution Approach 1:
The patent applies local quality by introducing dummy pillars at specific locations within the conductive structure rather than uniformly increasing pattern density everywhere. This allows electrical performance to be maintained in functional areas while creating localized regions with adjusted pattern density that compensate for CMP erosion. The dummy pillars are placed strategically to achieve the right balance between electrical performance and erosion prevention.
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 top surface erosion by up to 90-95% and maintains surface flatness, improving the quality and yield of semiconductor devices.
Implementation Method 1
The mechanical abrasion and chemical reactions work together to remove unwanted material
Implementation Method 2
Chemical Mechanical Polishing (CMP) combines aspects of both mechanical grinding and chemical etching
Data Source
AI summary
A wiring structure includes a first dielectric structure, a metal feature, a second dielectric structure and a metal pattern. The metal feature is embedded in the first dielectric structure. The second dielectric structure is disposed above the first dielectric structure and including dummy pillars and a main portion. The metal pattern is disposed above the first dielectric and including a conductive structure electrically connected with the metal feature. The dummy pillars are embedded in the conductive structure, and the main portion is surrounding the conductive structure.