Boron-Doped Tungsten Gapfill for Void-Free Semiconductor Features
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Solution Overview
Problem
Conventional tungsten deposition processes in semiconductor manufacturing face challenges in producing void-free and seam-free features, especially as feature sizes decrease, leading to performance and reliability issues due to voids and seams formed during the deposition process.
Innovation Solution
A method involving a tungsten-containing layer with a nucleation layer containing boron and tungsten, and a fill layer, where the tungsten-containing layer has a resistivity of 16 μΩ·cm or less and a thickness of 200 Å to 600 Å, is used. This layer is formed using a processing system that performs nucleation, inhibition treatment, and bulk tungsten deposition without transferring the substrate between chambers, utilizing activated nitrogen species and remote plasma sources to control deposition profiles and inhibit tungsten nucleation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional tungsten deposition processes are used, then tungsten features can be formed, but voids and seams are generated during deposition
Solution Approach 1:
The deposition process is divided into two distinct stages: nucleation stage and fill stage. The nucleation layer is formed first with controlled tungsten deposition and boron incorporation, followed by the fill stage that completes the gapfill. This segmentation allows optimization of each stage independently to prevent void and seam formation.
Solution Approach 2:
The patent employs dynamic adjustment of deposition parameters including gas flow rates (WF6, B2H6, H2), pressure, and temperature during the deposition process. The boron to tungsten ratio is controlled within specific ranges (1:4 to 1:1) to optimize nucleation and prevent defects. These parameter changes enable precise control over film quality and resistivity.
2Productivity
If feature size is decreased to increase circuit density, then device capacity increases, but voids and seams become amplified and affect performance
Solution Approach 1:
The patent creates a nucleation layer with specific local properties (boron incorporation, controlled thickness, specific resistivity range) that differs from the subsequent fill layer. This local quality control in the nucleation stage prepares the surface for defect-free fill deposition, ensuring high feature quality even at reduced dimensions.
Solution Approach 2:
The nucleation layer is formed as a preliminary step before the main fill deposition. This preliminary action incorporates boron into the tungsten matrix and creates a controlled surface morphology that prevents void and seam formation during subsequent fill, ensuring high-quality features at small dimensions.
3Length of moving object
If tungsten layer thickness is reduced, then device scaling is achieved, but resistivity control becomes challenging
Solution Approach 1:
The patent controls resistivity by adjusting the boron to tungsten ratio (1:4 to 1:1) and deposition parameters during the nucleation and fill stages. By varying these parameters, the resistivity is maintained within 16 μΩ·cm or less across different thicknesses from 200 Å to 600 Å, achieving both scaling and resistivity control.
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
The method achieves void-free and seam-free tungsten gapfill with reduced resistivity and surface roughness, maintaining low resistivity across various film thicknesses and enhancing the reliability and performance of semiconductor devices.
Implementation Method 1
conventional tungsten deposition processes
Implementation Method 2
utilizing activated nitrogen species and remote plasma sources to control deposition profiles and inhibit tungsten nucleation
Data Source
AI summary
A structure of a substrate is provided including a tungsten-containing layer including a nucleation layer and a fill layer. The nucleation layer is disposed along sidewalls of the opening. The nucleation layer includes boron and tungsten. The fill layer is disposed over the nucleation layer within the opening. The tungsten-containing layer includes a resistivity of about 16 μΩ·cm or less. The tungsten-containing layer has a thickness of about 200 Å to about 600 Å. The tungsten-containing layer thickness is half a width of the tungsten-containing layer disposed within the opening between opposing sidewall portions of the opening.