Tungsten Gap Fill Using Hydrogen Plasma to Prevent Voids
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Solution Overview
Problem
Conventional tungsten metal gap fill processes in the semiconductor industry are prone to voids due to early pinch-off at overhangs, leading to higher stack resistivity and reduced device performance.
Innovation Solution
A method involving a discontinuous liner layer deposition via PVD, followed by a hydrogen plasma process to form silicon-hydrogen bonds, and subsequent bulk tungsten layer deposition without a nucleation layer using ALD or CVD, ensuring void-free gap fill in silicon-containing dielectric layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional tungsten metal gap fill processes are used, then tungsten can be deposited to fill features, but voids form due to early pinch-off at overhangs
Solution Approach 1:
A liner layer is deposited on the feature walls before the bulk tungsten fill process. This preliminary liner layer prevents void formation by providing a foundation that eliminates early pinch-off at overhangs during subsequent tungsten deposition, ensuring complete feature filling without voids
Solution Approach 2:
The liner layer acts as an intermediary between the feature wall and the bulk tungsten layer. It mediates the deposition process by preventing direct contact issues between tungsten and the feature wall, thereby eliminating void formation while maintaining good electrical contact
2Reliability
If a nucleation layer is deposited before bulk tungsten fill, then void-free gap fill can be achieved, but stack resistivity increases due to high resistance of the nucleation layer
Solution Approach 1:
The invention extracts and eliminates the nucleation layer from the conventional gap fill process. By using a liner layer instead, the process achieves void-free filling without introducing the high-resistance nucleation layer that increases stack resistivity, thereby removing the harmful electrical resistance effect
Solution Approach 2:
The liner layer serves as a temporary, disposable element that performs its function during deposition and then becomes part of the final structure. Unlike a nucleation layer that remains as a high-resistance component, the liner layer is designed to be conductive and integrated into the final low-resistance tungsten structure
3Manufacturing precision
If discontinuous liner layer is deposited via PVD followed by hydrogen plasma treatment, then void-free tungsten fill is achieved without nucleation layer, but process complexity increases
Solution Approach 1:
The liner layer deposition and hydrogen plasma treatment are merged into a integrated process sequence within the same PVD chamber. The discontinuous liner layer is deposited via PVD, then hydrogen plasma is introduced to convert it to a continuous conductive layer, achieving void-free fill functionality while consolidating process steps
Solution Approach 2:
The process utilizes parameter changes by introducing hydrogen plasma to transform the liner layer from a discontinuous PVD-deposited state to a continuous conductive state. This parameter change (chemical composition and structural continuity) enables void-free tungsten fill without requiring a separate nucleation layer deposition process
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 achieves void-free tungsten gap fill, reducing stack resistivity and enhancing device performance by eliminating the need for high-resistance nucleation layers.
Implementation Method 1
depositing a discontinuous liner layer in the feature via a physical vapor deposition (PVD) process
Implementation Method 2
performing a hydrogen plasma process in a second process chamber to form silicon-hydrogen bonds on surfaces of the feature
Implementation Method 3
form silicon-hydrogen bonds on surfaces of the feature
Implementation Method 4
depositing a bulk tungsten layer on the discontinuous liner layer and over the silicon-hydrogen bonds to fill the feature with tungsten via an atomic layer deposition (ALD) process
Data Source
AI summary
Embodiments of methods and associated apparatus for filling features in a silicon-containing dielectric layer of a substrate are provided herein. In some embodiments, a method of filling features in a silicon-containing dielectric layer of a substrate includes: depositing a discontinuous liner layer in the feature via a physical vapor deposition (PVD) process in a first process chamber; performing a hydrogen plasma process in a second process chamber to form silicon-hydrogen bonds on surfaces of the feature not covered by the discontinuous liner layer; and depositing a bulk tungsten layer on the discontinuous liner layer and over the silicon-hydrogen bonds to fill the feature with tungsten in a third process chamber.