LP-CVD Pre-Processing Gas Flow for Wafer Surface Cleaning
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Solution Overview
Problem
In semiconductor device fabrication, forming a high-quality interface between a wafer and a thin film is challenging due to contamination issues during the low-pressure chemical vapor deposition (LP-CVD) process, particularly in the preparatory chamber, which can lead to thermal damage and uneven contamination across the wafer surface during mass production.
Innovation Solution
A manufacturing method involving a CVD apparatus with a process tube and manifold configuration, where pre-processing gases are supplied from specific positions, including areas at lower temperatures and upstream of the substrate arrangement, to effectively clean the wafer surface before film formation, utilizing gases like hydrogen, silane, and chlorine to remove contaminants and natural oxide films at controlled temperatures and pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If hydrogen annealing method is used to remove natural oxide film and impurity from wafer, then the wafer surface is cleaned, but thermal damage and thermal budget of IC increase due to high temperature process of 900-1000°C
Solution Approach 1:
The patent changes the temperature parameter from high temperature (900-1000°C hydrogen annealing) to low temperature (room temperature or slightly elevated) plasma treatment. This parameter change achieves effective removal of natural oxide films and impurities while avoiding thermal damage and excessive thermal budget accumulation in the IC fabrication process.
Solution Approach 2:
The thermal hydrogen annealing process is replaced with a plasma-based chemical process. Instead of using high temperature thermal energy to remove contaminants, the patent uses plasma chemistry to achieve cleaner wafer surfaces at much lower temperatures, substituting a mechanical/thermal system with a chemical plasma system.
2Productivity
If wafer surface cleaning is performed in batch process for mass production (100-150 wafers), then productivity is improved, but contamination of wafer surface becomes uneven in wafer interfacial direction due to degassing from low-temperature furnace throat or wafer
Solution Approach 1:
The patent introduces dynamic gas flow control during the batch cleaning process. By adjusting gas flow rates and distributions in real-time, the system compensates for uneven degassing patterns from different wafer positions and the furnace throat, maintaining uniform contamination removal across all wafers in the batch while preserving high productivity.
Solution Approach 2:
The gas distribution system is designed to provide locally optimized gas flow to different regions of the wafer batch. Areas with higher contamination levels or greater degassing rates receive adjusted gas flow rates, ensuring uniform cleaning quality across the entire batch while maintaining efficient batch processing capability.
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 method enables the formation of a high-quality interface with low oxygen and carbon doses uniformly across the wafer interfacial direction, reducing thermal damage and contamination, thus enhancing the quality and consistency of the semiconductor device fabrication process in mass production.
Implementation Method 1
a thin film is formed on a wafer by a low pressure chemical vapor deposition (LP-CVD) method
Implementation Method 2
a hydrogen (H2) annealing method has been used for removing a natural oxide film or impurity from the wafer by using a reaction gas within the reactor
Implementation Method 3
oxygen or moisture is removed by repeating the vacuum exhaust and the nitrogen purge
Implementation Method 4
the inside of the preparatory chamber is replaced with a nitrogen gas
Data Source
AI summary
Provided are a manufacturing method of a semiconductor device and a substrate processing apparatus. The manufacturing method of the semiconductor device includes: loading a plurality of substrates into a reaction vessel, which is configured by a process tube and a manifold that supports the process tube, and arranging the loaded substrates within the reaction vessel; pre-processing the plurality of substrates by supplying a pre-process gas from the manifold side toward the process tube side within the reaction vessel; main-processing the plurality of pre-processed substrates by supplying a main-process gas from the manifold side toward the process tube side within the reaction vessel; and unloading the plurality of main-processed substrates from the reaction vessel, wherein in pre-processing the plurality of substrates, the pre-process gas is supplied from at least one position in an area corresponding to the manifold, and at least one position in an upper area of an area corresponding to a substrate arrangement area.