Pulsed Source Gas Supply for Vertical Batch CVD Film Formation
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Solution Overview
Problem
Conventional film formation methods in vertical batch CVD apparatuses face challenges in improving film formation rate and quality, particularly in controlling silicon concentration and safely supplying large amounts of source gas without exceeding pressure limits, leading to inefficiencies and potential gas leaks.
Innovation Solution
A method and apparatus for film formation in a vertical batch CVD apparatus that alternately supplies a source gas and a reactive gas, with multiple adsorption and reaction steps, using a buffer tank to intermittently charge and discharge the source gas, ensuring safe pressure management and continuous reactive gas supply, while maintaining shut-off states to optimize film formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a large amount of source gas is supplied to improve film formation rate, then productivity increases, but pressure control becomes difficult and gas leakage risk increases
Solution Approach 1:
The source gas supply is divided into multiple small pulses instead of one large continuous supply. The gas supply unit supplies source gas in a pulsed manner with each pulse being a small amount, and this is repeated multiple times to achieve the desired total dosage. This segmentation allows maintaining high film formation rate while avoiding pressure control issues and gas leakage risks associated with large single-dose supply.
Solution Approach 2:
The source gas is supplied periodically in repeated cycles rather than continuously. Each cycle consists of a supply period followed by a non-supply period, creating a periodic action pattern. This periodic supply method enables the system to achieve high overall film formation rate while maintaining safe pressure levels during each individual supply pulse, thus resolving the contradiction between productivity and safety.
2Productivity
If source gas is supplied continuously to maintain high film formation rate, then productivity improves, but silicon concentration control becomes difficult
Solution Approach 1:
The continuous source gas supply is segmented into discrete pulsed doses. By controlling the number of pulses, duration of each pulse, and intervals between pulses, the system can precisely control the total amount of source gas supplied while maintaining high film formation rate. This segmentation enables independent control of both productivity and silicon concentration parameters.
Solution Approach 2:
The gas supply system transitions from a static continuous supply mode to a dynamic pulsed supply mode. The supply parameters (pulse duration, frequency, number of pulses) can be dynamically adjusted based on process requirements, enabling flexible control over both film formation rate and silicon concentration according to different manufacturing needs.
3Manufacturing precision
If multiple gas supply operations are performed to increase film thickness, then film quality improves, but process time increases
Solution Approach 1:
The pulsed source gas supply method maintains continuous useful action by eliminating unnecessary idle time between gas supply cycles. The repeated pulsed supply ensures that the reaction proceeds efficiently during each pulse while minimizing non-productive time, thereby achieving high-quality thick films without proportionally increasing total process time.
Solution Approach 2:
The periodic pulsed gas supply creates an optimized rhythm of reaction and recovery phases. Each pulse delivers source gas for film formation, followed by a non-supply period that allows for reaction completion and system preparation for the next pulse. This periodic action pattern achieves high film quality through multiple supply operations while minimizing total process time through efficient cycling.
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 enhances film formation rate by up to 60% and allows precise control of silicon concentration, ensuring safe operation by preventing pressure exceedance and effectively removing harmful exhaust gases, thus improving film quality and process safety.
Implementation Method 1
an adsorption step of performing supply of the source gas to the process field, thereby adsorbing the source gas onto a surface of the target substrates
Implementation Method 2
a reaction step of performing supply of the reactive gas to the process field, thereby causing the reactive gas to react with the source gas adsorbed on the surface of the target substrates
Data Source
AI summary
A film formation method, in a vertical batch CVD apparatus, is preset to repeat a cycle a plurality of times to laminate thin films formed by respective times. The cycle alternately includes an adsorption step of adsorbing a source gas onto a surface of the target substrates and a reaction step of causing a reactive gas to react with the adsorbed source gas. The adsorption step is arranged to make a plurality of times a supply sub-step of performing supply of the source gas to the process field with an intermediate sub-step of stopping supply of the source gas to the process field interposed therebetween, while maintaining a shut-off state of supply of the reactive gas. The reaction step is arranged to continuously perform supply of the reactive gas to the process field, while maintaining a shut-off state of supply of the source gas.