Source/Drain Contact Structure for Silicide-Safe CVD Filling
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Solution Overview
Problem
The increasing density of integrated circuits (ICs) leads to challenges in fabricating low resistance contacts, as precursors used in chemical vapor deposition (CVD) processes can induce silicide damage, resulting in increased source/drain contact resistance and degraded device performance.
Innovation Solution
A method involving physical vapor deposition (PVD) to form a bottom conductive feature over the silicide layer, followed by the deposition of a glue layer and then a top conductive feature using CVD, which reduces silicide damage and enhances adhesion, thereby minimizing contact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If CVD process is used to deposit metal layers, then conformal coverage and filling capability are improved, but silicide damage occurs resulting in increased contact resistance
Solution Approach 1:
A PVD metal layer is deposited over the silicide contact before CVD processing to protect the silicide from damage by CVD precursors. This preliminary protective layer prevents harmful interactions while allowing the subsequent CVD process to proceed with its conformal coverage advantages.
Solution Approach 2:
The PVD metal layer serves as an intermediary barrier between the CVD precursors and the silicide contact. This intermediate layer allows the CVD process to achieve conformal coverage without directly exposing the silicide to damaging precursor chemicals.
2Object-affected harmful factors
If PVD process is used to deposit metal layers, then silicide damage is reduced, but adhesion between metal and dielectric layers deteriorates
Solution Approach 1:
The metal deposition process is segmented into multiple stages: first PVD to protect silicide, then a thin glue layer for adhesion, then CVD for conformal coverage. Each segment performs a specific function that collectively solves both the silicide damage and adhesion problems.
Solution Approach 2:
A glue layer is deposited as an intermediary between the PVD metal layer and the CVD metal layer. This glue layer provides the necessary adhesion to the dielectric sidewalls while allowing the PVD layer to protect the silicide and the CVD layer to provide conformal coverage.
3Productivity
If source/drain contacts are arranged closer to gate structures, then IC density and functionality are improved, but contact resistance increases due to silicide damage
Solution Approach 1:
The PVD protective metal layer is deposited in advance before CVD processing to prevent silicide damage. This allows source/drain contacts to be positioned closer to gate structures without sacrificing contact reliability, as the silicide is protected from precursor-induced damage.
Solution Approach 2:
The contact structure uses a composite approach with multiple material layers (PVD metal, glue layer, CVD metal) to achieve both low contact resistance through silicide protection and good adhesion, enabling higher IC density without compromising reliability.
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 silicide damage and contact resistance, enhancing the performance and longevity of semiconductor devices by protecting the silicide layer during CVD metal deposition and improving adhesion between metal and dielectric layers.
Implementation Method 1
performing a physical vapor deposition process to form a first conductive feature over the silicide layer
Implementation Method 2
performing a chemical vapor deposition process to form a second conductive feature in the opening and in contact with the glue layer
Data Source
AI summary
In a semiconductor structure, a first conductive feature is formed in a trench by PVD and a glue layer is then deposited on the first conductive feature in the trench before CVD deposition of a second conductive feature there-over. The first conductive feature acts as a protection layer to keep silicide from being damaged by later deposition of metal or a precursor by CVD. The glue layer extends along the extent of the sidewall to enhance the adhesion of the second conductive features to the surrounding dielectric layer.