Integrated Tungsten Contact Formation via Atmospheric-Free Process Flow
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Solution Overview
Problem
Traditional metal contact formation processes result in oxidation of the tungsten liner layer, leading to high contact resistance and poor gap fill due to the formation of an oxide layer, which is exacerbated as feature sizes shrink, causing reliability issues and increased resistance in integrated circuits.
Innovation Solution
A method involving the deposition of a tungsten liner layer within a first substrate process chamber using a plasma formed from a metal organic tungsten precursor or fluorine-free tungsten halide precursor, followed by transferring the substrate without exposure to the atmosphere and depositing a tungsten fill layer using a tungsten fluoride precursor, thereby avoiding oxidation and reducing contact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional separated processing systems are used for tungsten liner layer deposition, then process flexibility is maintained, but the tungsten liner layer is exposed to atmosphere causing oxidation and high contact resistance
Solution Approach 1:
The patent combines multiple processing steps (tungsten liner layer deposition, intermediate layer deposition, and tungsten fill layer deposition) into a single integrated processing system with multiple chambers. This allows continuous processing without atmospheric exposure, preventing oxidation of the tungsten liner layer and reducing contact resistance while maintaining process control and flexibility
2Reliability
If tungsten liner layer is deposited and then exposed to atmosphere before CVD tungsten deposition, then separate processing systems can be used, but an oxide layer forms increasing contact resistance to greater than 1E3 μOhm-cm
Solution Approach 1:
The patent implements continuous processing where the substrate is transferred through multiple chambers without atmospheric exposure. The tungsten liner layer is deposited, then immediately followed by intermediate layer deposition and CVD tungsten fill layer deposition in sequence, eliminating the atmospheric exposure step that causes oxidation and high contact resistance
3Manufacturing precision
If oxide layer forms on tungsten liner layer surface, then atmosphere exposure is simple, but incubation delay increases causing voids or large seams during CVD tungsten gap fill
Solution Approach 1:
The patent deposits an intermediate layer (such as tungsten oxide or tungsten sub-oxide) on the tungsten liner layer before CVD tungsten deposition. This intermediate layer serves as a nucleation layer that reduces the incubation delay for CVD tungsten deposition, preventing voids and large seams during gap fill while maintaining manufacturing precision
4Length of moving object
If feature size shrinks to 20 nm level, then device integration increases, but oxidized liner material contributes significantly to contact resistance limiting device driving current
Solution Approach 1:
The patent uses an integrated processing system that maintains a controlled atmosphere throughout all deposition steps. The substrate is transferred through chambers without atmospheric exposure, creating an inert environment that prevents oxidation of the tungsten liner layer even at 20 nm feature sizes, thereby maintaining low contact resistance and adequate device driving current
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, minimizes voids and seams during gap fill, and enhances the reliability of metal contacts and devices by maintaining the tungsten liner layer in a non-oxidized state, particularly beneficial for device nodes at 10 nm or less.
Implementation Method 1
exposing a substrate, within a first substrate process chamber, to a plasma formed from a first gas comprising a metal organic tungsten precursor gas or a fluorine-free tungsten halide precursor to deposit a tungsten liner layer
Implementation Method 2
exposing the substrate to a second gas comprising a tungsten fluoride precursor to deposit a tungsten fill layer atop the tungsten liner layer
Data Source
AI summary
Methods for forming metal contacts having tungsten liner layers are provided herein. In some embodiments, a method of processing a substrate includes: exposing a substrate, within a first substrate process chamber, to a plasma formed from a first gas comprising a metal organic tungsten precursor gas or a fluorine-free tungsten halide precursor to deposit a tungsten liner layer, wherein the tungsten liner layer is deposited atop a dielectric layer and within a feature formed in a first surface of the dielectric layer of a substrate; transferring the substrate to a second substrate process chamber without exposing the substrate to atmosphere; and exposing the substrate to a second gas comprising a tungsten fluoride precursor to deposit a tungsten fill layer atop the tungsten liner layer.