TEOS Film Defect Elimination via Multi-Station PECVD
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Solution Overview
Problem
High throughput PECVD processes for depositing TEOS films often result in small bin defects due to insufficient wafer heating, which compromises film quality and yield, especially as device sizes shrink below 65 nanometers.
Innovation Solution
A multi-station sequential deposition process where the first station is dedicated to temperature soak with a purge gas, eliminating reactant gas flow to prevent TEOS condensation, and using Argon or other purge gases to maintain high throughput while minimizing defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If temperature soak time is increased to eliminate small bin defects, then film quality improves, but throughput decreases
Solution Approach 1:
The patent divides the deposition process into multiple stations, with the first station dedicated to temperature soak and subsequent stations performing deposition. This segmentation allows the wafer to be heated to the required temperature without losing time, as the temperature soak occurs in parallel with other processing steps at different stations, thereby maintaining high throughput while achieving defect-free films.
Solution Approach 2:
The patent performs temperature soak as a preliminary action in the first station before the wafer proceeds to deposition stations. By pre-heating the wafer to the optimal temperature range, the system ensures that subsequent deposition occurs at the correct temperature, eliminating small bin defects without extending the total process time, thus maintaining high throughput.
2Manufacturing precision
If reactant gas flow is maintained during temperature soak, then deposition continues, but TEOS condensation causes small bin defects
Solution Approach 1:
The patent extracts the reactant gas flow during the temperature soak phase in the first station, replacing it with a purge gas. This prevents TEOS condensation on the cold wafer surface, eliminating small bin defects. The deposition process is then resumed in subsequent stations where reactant gas flow is restored, maintaining deposition efficiency while achieving defect-free films.
Solution Approach 2:
The patent introduces an inert purge gas atmosphere during the temperature soak phase to prevent TEOS condensation. By creating an inert environment that excludes reactive TEOS vapor, the system prevents defect formation while still allowing the wafer to be heated to the required temperature. Deposition is then performed in a controlled reactive atmosphere in subsequent stations, maintaining efficiency.
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 process significantly reduces small bin defects and maintains high throughput, achieving defect levels below 30 particles greater than 0.16 microns and within-wafer non-uniformity of less than one percent, while supporting throughput of over 80 wafers per hour for thin dielectric films.
Implementation Method 1
Stopping the flow of reactant gas and flowing the purge gas for station 1 may eliminate TEOS condensation on a cold wafer surface
Implementation Method 2
TEOS oxide is often deposited by a plasma enhanced deposition chemical vapor deposition (PECVD) process
Implementation Method 3
Liquid TEOS is first vaporized in a preheater to about 150 degrees Celsius
Data Source
AI summary
This invention provides a high throughput PECVD process for depositing TEOS films in a multi-station sequential deposition chamber. The methods significantly reduce the number of particles in the TEOS films, thereby eliminating or minimizing small bin defects. The methods of the invention involve dedicating a first station for temperature soak while flowing purge gas. Stopping the flow of reactant gas and flowing the purge gas for station 1 eliminates TEOS condensation on a cold wafer surface and significantly reduces the number of defects in the film, particularly for short temperature soaks.