Batch CVD Method Reducing Source Gas Consumption
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Solution Overview
Problem
Conventional batch CVD methods face challenges in film quality, throughput, and source gas consumption, particularly due to excessive source gas consumption and inadequate planar uniformity of film thickness, especially when forming silicon oxide films using expensive source gases.
Innovation Solution
A modified batch CVD method and apparatus that includes a vertically long process container with a source gas supply system, a reactive gas supply system, and an exhaust system, where the cycle consists of an adsorption step with the source gas valve open, followed by an intermediate step of removing residual gas, a reaction step with the reactive gas valve open and gradually decreasing exhaust valve opening, and another intermediate step of removing residual gas, optimizing gas flow and pressure control to reduce source gas consumption and enhance film uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If conventional batch CVD method is used to form silicon oxide film, then film formation is achieved, but source gas consumption is excessive
Solution Approach 1:
The patent applies periodic action by dividing the film formation process into alternating adsorption steps and exhaust steps. During adsorption steps, source gas is supplied to deposit material on wafers, followed by exhaust steps that remove residual gas. This periodic cycling allows precise control of source gas exposure time and quantity, significantly reducing overall source gas consumption while maintaining uniform film deposition through controlled intermittent exposure rather than continuous gas flow.
Solution Approach 2:
The patent employs parameter changes by dynamically adjusting the valve opening degree of the exhaust system during different process phases. Specifically, the exhaust valve opening is increased during exhaust steps to rapidly remove residual source gas and reduce consumption, while being optimized during adsorption steps to maintain proper pressure and uniform gas distribution for consistent film thickness. This dynamic parameter adjustment resolves the contradiction between reducing gas consumption and maintaining deposition uniformity.
2Manufacturing precision
If source gas is continuously supplied to ensure uniform film thickness, then manufacturing precision is improved, but source gas consumption increases
Solution Approach 1:
The periodic alternation between adsorption and exhaust steps ensures that source gas is supplied only when needed for film deposition, then rapidly removed. This prevents excessive source gas accumulation that would waste material, while the controlled adsorption phases ensure sufficient gas exposure for uniform film formation across the wafer surface, resolving the trade-off between precision and consumption.
Solution Approach 2:
The patent implements feedback control through monitoring and adjusting the exhaust valve opening degree based on process requirements. The exhaust system responds to residual gas levels by dynamically changing valve opening, ensuring that source gas is removed promptly after deposition phases while maintaining optimal conditions during adsorption. This feedback mechanism ensures uniform film thickness is achieved without excessive gas consumption.
3Reliability
If exhaust valve opening is kept constant, then operation simplicity is maintained, but ozone deactivation occurs and film quality deteriorates
Solution Approach 1:
The patent applies dynamics by making the exhaust valve opening degree variable rather than constant. The valve opening is dynamically adjusted based on the process phase: increased during exhaust steps to rapidly remove residual source gas and prevent ozone deactivation, and optimized during adsorption steps to maintain proper pressure. This dynamic adjustment prevents harmful chemical reactions while the automated control system manages the complexity, achieving reliable film quality without excessive operational burden.
Solution Approach 2:
The patent employs parameter changes by varying the exhaust valve opening degree as a controllable parameter throughout the process cycle. This parameter is changed from a constant value to a time-dependent variable that increases during exhaust phases to prevent ozone deactivation and is optimized during adsorption phases. The automated control system manages this parameter change, balancing the need for precise valve control with operational simplicity through programmatic management.
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 significantly reduces source gas consumption while maintaining high film quality and improving throughput, preventing ozone deactivation and ensuring uniform film thickness across semiconductor wafers, even on patterned surfaces.
Implementation Method 1
an adsorption step of adsorbing the source gas onto the target objects
Implementation Method 2
a reaction step of causing the reactive gas to react with the source gas adsorbed on the target objects
Implementation Method 3
exhausting gas from inside the process container by setting the exhaust valve open
Data Source
AI summary
A batch CVD method repeats a cycle including adsorption and reaction steps along with a step of removing residual gas. The adsorption step is preformed while supplying the source gas into the process container by first setting the source gas valve open for a first period and then setting the source gas valve closed, without supplying the reactive gas into the process container by keeping the reactive gas valve closed, and without exhausting gas from inside the process container by keeping the exhaust valve closed. The reaction step is performed without supplying the source gas into the process container by keeping the source gas valve closed, while supplying the reactive gas into the process container by setting the reactive gas valve open, and exhausting gas from inside the process container by setting the exhaust valve to gradually decrease its valve opening degree from a predetermined open state.