Uniform Tungsten Deposition via Nucleation and Etch-Back
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The deposition-etch-deposition process for tungsten layers in semiconductor manufacturing results in uneven thickness across wafers, leading to significant thickness fluctuations and residual fluorine residues affecting deposition quality.
Innovation Solution
A method and system involving a nucleation process, followed by a first deposition at a low temperature, etching back with a fluorine-containing gas, cleaning with hydrogen to remove residues, and a second deposition at a higher temperature to form a uniform tungsten layer, utilizing a system with multiple processing stations and controlled gas delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a deposition-etch-deposition process is used to improve gap filling properties, then gap filling is improved, but thickness uniformity deteriorates
Solution Approach 1:
A nucleation layer is formed prior to the main deposition process to prepare the substrate surface. This preliminary action ensures uniform metal deposition by creating a consistent foundation layer that promotes uniform growth during subsequent deposition steps, thereby maintaining thickness uniformity while achieving good gap filling properties.
Solution Approach 2:
The patent employs multiple deposition processes conducted at different temperatures. By varying the temperature parameter between deposition steps, the process optimizes both gap filling and thickness uniformity. The first deposition at a first temperature and second deposition at a second temperature creates controlled growth conditions that prevent excessive thickness variation.
2Ease of manufacture
If a deposition-etch-deposition process is used, then gap filling is improved, but thickness fluctuation increases
Solution Approach 1:
The nucleation layer formation serves as a preliminary action that stabilizes the substrate surface before main deposition. This preliminary preparation reduces variability in metal deposition across different wafers, thereby reducing thickness fluctuation and improving reliability while maintaining gap filling capability.
Solution Approach 2:
By conducting multiple deposition processes at different temperatures, the patent controls the deposition rate and growth characteristics. This parameter variation ensures consistent metal layer formation across wafers, reducing thickness fluctuation from ±300 Angstroms to ±100 Angstroms or better.
3Ease of manufacture
If etching back is performed to remove excess metal, then gap filling is improved, but residual fluorine residues are introduced
Solution Approach 1:
The patent uses a cleaning process with a reducing gas to convert the harmful residual fluorine residues into a removable form. The reducing gas reacts with the fluorine residues, transforming them into volatile compounds that can be easily removed, thereby eliminating the harmful effect while maintaining the benefits of the etch-back process.
Solution Approach 2:
A reducing gas is introduced as an intermediary substance between the etching process and the final metal deposition. This intermediary cleaning step removes residual fluorine compounds from the etch-back process, preventing contamination of subsequent deposition layers while preserving the gap filling improvements achieved through etch-back.
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 a more uniform tungsten layer thickness across wafers, reducing thickness fluctuations and eliminating residual fluorine, thereby improving deposition quality and consistency.
Implementation Method 1
performing a nucleation process on the substrate to form a nucleation layer of a metal
Implementation Method 2
performing a first deposition process at a first temperature on the nucleation layer to form a first metal layer
Implementation Method 3
etching back the first metal layer using a first gas
Implementation Method 4
cleaning the substrate including the etched back first metal layer using a second gas, wherein the second gas is a reducing gas
Data Source
AI summary
A system includes a deposition chamber comprising first, second, and third stations, a delivery system providing a substrate to the deposition chamber, a processing system processing the substrate, a controller controlling the delivery system and the processing system, and an etch chamber. The delivery system provides the substrate to the first station, where the processing system performs a nucleation process on the substrate to form a metal nucleation layer, the substrate is then provided by the delivery system to the second station, where the processing system performs a first deposition process at a first temperature to form a first metal layer, the delivery system provides the substrate including the first metal layer metal to the etch chamber, where the first metal layer is etched back using a first gas. The substrate is provided back to the first station, wherein it undergoes a cleaning process using a second gas.