Molybdenum Feature Fill Using Protective Mo Layers Against Oxidation
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Solution Overview
Problem
As semiconductor devices scale down to the 10 nm node and lower, line and via contact resistance in metal interconnects increases due to reduced current-carrying cross-section and electron scattering, and challenges in filling narrow features with current Cu or W process schemes.
Innovation Solution
Deposition processes involving a thin protective Mo layer using a molybdenum chloride (MoClx) precursor, followed by Mo deposition with a molybdenum oxyhalide (MoOyXz) precursor, and in-situ clean processes using MoClx to remove oxidation from underlying surfaces, enabling effective Mo fill without oxidation of the underlying surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current Cu or W process schemes are used to fill narrow features, then the manufacturing process is simple, but the contact resistance increases rapidly and filling challenges arise
Solution Approach 1:
The filling process is divided into multiple sequential steps: (1) in-situ cleaning to remove oxidation, (2) deposition of initial Mo layer using MoClx precursor, (3) feature fill using MoOyXz precursor. This segmentation allows each step to be optimized independently, achieving low contact resistance through proper surface preparation and controlled deposition
Solution Approach 2:
The in-situ cleaning step using MoClx precursor is performed before Mo deposition to remove oxidation from underlying surfaces. This preliminary action prevents oxidation-related contact resistance issues and ensures proper adhesion of the Mo layer to the substrate
2Productivity
If Mo deposition is performed using MoOyXz precursor on oxidized surfaces, then the deposition process is straightforward, but oxidation of the underlying surfaces occurs
Solution Approach 1:
An in-situ cleaning step using MoClx precursor is performed before Mo deposition to remove oxidation from the underlying surfaces. This preliminary action prevents oxidation during the subsequent MoOyXz-based deposition process, enabling high productivity without surface oxidation
Solution Approach 2:
The deposition process is conducted in a controlled atmosphere using MoClx precursor that creates a protective environment preventing oxidation of underlying surfaces during Mo fill using MoOyXz precursor
3Productivity
If device dimensions are scaled down to 10 nm node and lower, then the device density increases, but line and via contact resistance increases due to reduced cross-section
Solution Approach 1:
The invention changes the deposition parameters by using MoClx precursor for in-situ cleaning and initial layer deposition, then MoOyXz precursor for feature fill. This parameter change enables better control of deposition characteristics in narrow features, achieving low contact resistance despite reduced cross-section at 10 nm node and lower
Solution Approach 2:
The process applies different precursors for different purposes: MoClx for surface cleaning and initial layer, MoOyXz for bulk fill. This local quality approach optimizes each stage for its specific function, ensuring low contact resistance in the critical feature regions while maintaining high device density
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 reduces contact resistance by preventing oxidation of the underlying surfaces, facilitating better Mo integration and fill in narrow features, and is applicable to oxygen-sensitive surfaces like silicon and silicon-germanium.
Implementation Method 1
depositing an initial molybdenum film in the feature using a molybdenum halide precursor and a reducing agent
Implementation Method 2
at least partially filling the feature with molybdenum using a molybdenum oxyhalide precursor
Implementation Method 3
soaking the feature in a molybdenum halide precursor to remove oxide from the oxidized surface
Data Source
AI summary
Provided are deposition processes including deposition of a thin, protective Mo layer using a molybdenum chloride (MoClx) precursor. This may be followed by Mo deposition to fill the feature using a molybdenum oxyhalide (MoOyXz) precursor. The protective Mo layer enables Mo fill using an MoOyXz precursor without oxidation of the underlying surfaces. Also provided are in-situ clean processes in which a MoClx precursor is used to remove oxidation from underlying surfaces prior to deposition. Subsequent deposition using the MoClx precursor may deposit an initial layer and/or fill a feature.