Multi-Dosing Valve Gas Supply for ALD Step Coverage
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Solution Overview
Problem
In atomic layer deposition (ALD) processes, deposition gases often decompose before reaching the bottom surface of openings with high aspect ratios, leading to deteriorated step coverage in memory devices like VNAND, due to insufficient pressure and premature decomposition.
Innovation Solution
A gas supply system with multiple gas filling tanks and a multi-dosing valve assembly that sequentially supplies gases to the process chamber, maintaining high pressure and preventing backflow to ensure effective deposition, thereby improving step coverage and Unit Per Equipment Hour (UPEH) performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If a single gas supply source is used, then the device complexity is low, but the gas pressure is insufficient causing decomposition before reaching the bottom surface
Solution Approach 1:
The gas supply system is divided into multiple gas filling tanks (first gas filling tank, second gas filling tank, etc.) that can be charged and discharged sequentially. This segmentation allows the system to maintain higher pressure by refilling gas from additional tanks when the first tank is depleted, thereby preventing gas decomposition before reaching the bottom surface of high aspect ratio openings.
Solution Approach 2:
The gas filling tanks are pre-charged with deposition gas before the deposition process begins. This preliminary action ensures that when gas is needed during deposition, it is already available at the required pressure, eliminating the need for real-time compression and preventing gas decomposition due to pressure loss.
2Reliability
If gas is supplied continuously, then the deposition process is efficient, but gas decomposition occurs before reaching the target surface
Solution Approach 1:
The system employs periodic charging and discharging of multiple gas filling tanks in sequence. When the first tank is discharged, the second tank is charged and then discharged, creating a periodic replenishment cycle. This ensures continuous supply of fresh, high-pressure gas to the deposition chamber, maintaining both deposition quality and efficiency without gas decomposition.
3Manufacturing precision
If the gas supply system is simplified, then the ease of manufacture is high, but step coverage deteriorates due to gas decomposition
Solution Approach 1:
The gas supply system is segmented into multiple independently controllable gas filling tanks with separate charging and discharging mechanisms. This segmentation allows precise control over gas flow timing and pressure, ensuring that fresh high-pressure gas reaches the bottom surface of high aspect ratio openings, thereby improving step coverage while maintaining a relatively simple overall system architecture.
4Manufacturing precision
If equipment is remodeled to improve gas supply, then the step coverage improves, but the productivity decreases due to equipment downtime
Solution Approach 1:
Gas filling tanks are pre-charged with deposition gas during idle periods or between production batches. This preliminary charging action ensures that when deposition is required, the system can immediately switch to using pre-charged tanks without requiring equipment remodeling or downtime, thereby maintaining both improved step coverage and high productivity.
Solution Approach 2:
The system uses multiple gas filling tanks that can be operated in sequence. When one tank is depleted, the system automatically switches to another pre-charged tank, effectively discarding the depleted tank temporarily while recovering productivity through continuous operation with alternative tanks. This eliminates downtime associated with equipment remodeling or single-tank recharging.
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 solution enhances the step coverage characteristics of thin films and improves UPEH by maintaining high pressure and preventing gas decomposition, allowing for efficient layer deposition without the need for equipment remodeling.
Implementation Method 1
Each of the gas filling tanks may be pressurized with a first gas from the first gas supply source
Implementation Method 2
a multi-dosing valve assembly connected to outlet portions of the gas filling tanks that is configured to supply, sequentially, the first gas from the gas filling tanks to a process chamber
Data Source
AI summary
A gas supply for a layer deposition apparatus including a plurality of charge distribution lines connected to a first gas supply source and a plurality of gas filling tanks respectively connected to the charge distribution lines is disclosed. Each of the gas filling tanks may be pressurized with a first gas from the first gas supply source, and a gas supply line connected to a second gas supply source. The apparatus may include a multi-dosing valve assembly connected to outlet portions of the gas filling tanks and configured to supply, sequentially, the first gas from the gas filling tanks to a process chamber. The multi-dosing valve assembly may include a flow path block having a main supply line connected to the process chamber and a backflow prevention valve block fastened to the flow path block and having an opening/closing valve therein.