Selective Cobalt Deposition via Thermal Process and Surface Passivation
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Solution Overview
Problem
Conventional cobalt deposition processes using plasma damage surrounding dielectric materials with low dielectric constants, leading to reliability issues in metal interconnects.
Innovation Solution
A method involving thermal deposition of a cobalt layer on a substrate, preceded by surface passivation with a reducing gas or UV-activated reducing gas to remove contaminants and improve dielectric constant, ensuring selective cobalt deposition without damaging low-k dielectric materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If plasma deposition process is used to deposit cobalt layer, then cobalt deposition is achieved, but damage occurs to surrounding dielectric materials with low dielectric constant
Solution Approach 1:
The patent changes the deposition method from plasma-based to thermal-based, altering the physical parameters of the deposition process. This parameter change allows cobalt deposition without the harmful plasma effects that damage low-k dielectric materials, while maintaining the necessary adhesion properties through controlled thermal deposition conditions
Solution Approach 2:
The patent substitutes the plasma deposition mechanism with a thermal deposition mechanism. By replacing the plasma-based process with a thermally-driven process, the harmful effects on dielectric materials are eliminated while the cobalt layer deposition and adhesion functions are preserved through thermal energy control
2Manufacturing precision
If reducing gas or UV-activated reducing gas is used to clean surfaces, then contaminants are removed and dielectric constant is improved, but additional process steps are required
Solution Approach 1:
The patent combines multiple functions into integrated process steps. The reducing gas treatment serves both to remove contaminants and to improve dielectric constant, while the passivation layer formation is integrated with the thermal deposition process. This merging reduces the total number of separate process steps while achieving multiple objectives
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
Enhances the adhesion and reliability of metal-dielectric interfaces by improving the dielectric constant of low-k materials and avoiding damage during cobalt layer deposition.
Implementation Method 1
exposing a substrate, comprising a dielectric layer having an exposed dielectric surface and a metal layer having an exposed metal surface, to a reducing gas at a temperature of about 200 to about 800 degrees Celsius, or to a plasma formed from a reducing gas, or to a UV light activated reducing gas to remove contaminants from the copper surface and from the dielectric surface
Implementation Method 2
exposing the substrate to a first process gas to passivate the exposed dielectric surface
Implementation Method 3
selectively depositing a cobalt layer atop the metal surface using a thermal deposition process
Data Source
AI summary
Methods for selectively depositing a cobalt layer are provided herein. In some embodiments, methods for selectively depositing a cobalt layer include: exposing a substrate to a first process gas to passivate an exposed dielectric surface, wherein the substrate comprises a dielectric layer having an exposed dielectric surface and a metal layer having an exposed metal surface; and selectively depositing a cobalt layer atop the exposed metal surface using a thermal deposition process.