Electroless Copper Deposition Void-Free Filling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
As feature sizes in semiconductor devices decrease, existing methods for filling metal interconnects in low-k dielectric layers often result in voids, making it difficult to avoid these defects effectively.
Innovation Solution
A method involving directional and selective deposition of a metal seed layer on features, followed by selective removal of the seed layer from tops and overhangs using wet etch or CMP, and subsequent electroless deposition to fill the features, ensuring minimal sidewall deposition and reduced voids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional electroless deposition is used to fill metal interconnects in low-k dielectric layers, then the features can be filled with copper, but voids form in the filled features making it difficult to avoid defects
Solution Approach 1:
A metal seed layer is deposited on the features before the electroless copper deposition process. This preliminary seed layer provides a nucleation surface that promotes uniform copper deposition and prevents void formation during the filling process, thereby improving both filling completeness and reducing defects
Solution Approach 2:
The metal seed layer is selectively deposited on specific regions of the features (tops and bottoms) while controlling deposition on sidewalls. This localized deposition strategy ensures proper nucleation sites are created where needed while minimizing unwanted deposition elsewhere, leading to void-free filling and reduced defects
2Reliability
If metal seed layer is deposited directionally and selectively on features, then voids are reduced in filled features, but additional process steps are required
Solution Approach 1:
The directional and selective deposition of the metal seed layer is integrated with the existing electroless deposition process flow. The seed layer deposition uses similar chemical vapor deposition or atomic layer deposition techniques already employed in the manufacturing line, merging the new step with existing processes to minimize added complexity while achieving void 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 effectively reduces voids in metal contacts within features, enhancing the reliability and performance of semiconductor devices by ensuring complete filling with minimal defects.
Implementation Method 1
A metal seed layer is directionally and selectively deposited on tops and bottoms of features with respect to sidewalls of the features
Implementation Method 2
An electroless copper or copper alloy deposition is provided to fill the features, wherein the electroless copper or copper alloy deposition first deposits on the copper or copper alloy seed layer on bottoms of the features
Data Source
AI summary
A method for providing metal filled features in a layer is provided. A metal seed layer is deposited on tops and bottoms of the features. Metal seed layer on tops of the features and overhangs is removed without removing metal seed layer on bottoms of features. An electroless deposition of metal is provided to fill the features, wherein the electroless deposition first deposits on the metal seed layer on bottoms of the features.