Ruthenium CVD Deposition via Thin Ru Barrier Layer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for depositing ruthenium using Chemical Vapor Deposition (CVD) on copper layers result in void formation and corrosion due to carbon incorporation and the subsequent hydrogen annealing process, which is exacerbated by feature size reduction.
Innovation Solution
The method involves depositing a thin ruthenium layer using Plasma-Enhanced Chemical Vapor Deposition (PECVD) with limited carbon incorporation, followed by a copper seed layer via Physical Vapor Deposition (PVD) and annealing to achieve conformal coverage without the need for hydrogen annealing, thereby avoiding corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If CVD is used to deposit ruthenium on copper layers, then better control of film morphology and step coverage is achieved, but void formation and corrosion occur in underlying copper layers
Solution Approach 1:
A thin ruthenium layer is deposited as an intermediary barrier between the copper layer and the CVD ruthenium deposition process. This intermediary layer prevents direct interaction between the copper and carbon-containing precursors, eliminating void formation and corrosion while allowing the CVD process to proceed with its superior film morphology control and step coverage capabilities
Solution Approach 2:
The ruthenium metallization structure is segmented into multiple layers: a thin initial ruthenium layer (5-20 nm) deposited by PECVD or atomic layer deposition, followed by a thicker ruthenium layer deposited by CVD. This segmentation allows the first thin layer to protect the copper from carbon incorporation while the second layer provides the desired thick ruthenium metallization with excellent step coverage
2Object-affected harmful factors
If a thicker copper seed layer is deposited prior to ruthenium CVD, then void formation is avoided, but scaling problems occur for features below 40 nm
Solution Approach 1:
Instead of increasing copper layer thickness to prevent void formation, a thin ruthenium layer is introduced as an intermediary protective barrier. This allows the copper seed layer to remain thin (suitable for sub-40 nm scaling) while the ruthenium layer prevents carbon incorporation and void formation during subsequent CVD ruthenium deposition
3Quantity of substance
If hydrogen annealing is performed after ruthenium deposition, then carbon removal is achieved, but corrosion of underlying copper layers occurs
Solution Approach 1:
A thin ruthenium layer is deposited in advance before the main CVD ruthenium deposition. This preliminary ruthenium layer acts as a protective barrier that prevents carbon incorporation from the outset, eliminating the need for subsequent hydrogen annealing and thereby preventing corrosion of the underlying copper layer
Solution Approach 2:
The patent converts the potentially harmful CVD process into a beneficial deposition method by introducing a thin ruthenium barrier layer first. This barrier transforms the CVD process from a source of carbon contamination into a method that provides excellent step coverage and film morphology control without harmful side effects
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 allows for conformal ruthenium deposition without carbon-related issues, enabling proper reflow of the copper seed layer and preventing void formation in underlying copper layers, particularly beneficial for smaller feature sizes.
Implementation Method 1
generating a plasma from the first deposition gas to deposit a first ruthenium layer over the barrier layer
Implementation Method 2
flowing a first deposition gas into a processing chamber, the first deposition gas comprising a ruthenium containing precursor
Implementation Method 3
annealing the substrate at a second temperature
Implementation Method 4
depositing a copper seed layer over the second ruthenium layer
Data Source
AI summary
Methods for depositing ruthenium by a PECVD process are described herein. Methods for depositing ruthenium can include positioning a substrate in a processing chamber, the substrate having a barrier layer formed thereon, heating and maintaining the substrate at a first temperature, flowing a first deposition gas into a processing chamber, the first deposition gas comprising a ruthenium containing precursor, generating a plasma from the first deposition gas to deposit a first ruthenium layer over the barrier layer, flowing a second deposition gas into the processing chamber to deposit a second ruthenium layer over the first ruthenium layer, the second deposition gas comprising a ruthenium containing precursor, depositing a copper seed layer over the second ruthenium layer and annealing the substrate at a second temperature.