ALD Gaede Pump Pressure Modulation
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Solution Overview
Problem
Conventional atomic layer deposition (ALD) processes face a tradeoff between faster injection and sweep sub-steps at lower pressures and higher gas flow rates, and faster reaction sub-steps at higher pressures and lower gas flow rates, leading to inefficiencies and precursor waste, with existing modulation techniques being too slow for sub-second cycle times.
Innovation Solution
The use of Gaede pump stages to modulate pressures and gas flow rates during ALD sub-steps, allowing for higher precursor pressures and lower flow rates during reaction sub-steps, and lower pressures and higher flow rates during sweep sub-steps, facilitated by a synchronously modulated flow compression draw system with a single-impeller, low-volume Gaede pump stage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If lower pressures and higher gas flow rates are used, then injection and sweep sub-steps are faster, but reaction sub-steps become slower and precursor waste increases
Solution Approach 1:
The patent applies dynamic pressure modulation by switching between two distinct pressure regimes: high pressure during reaction sub-steps to maximize deposition rate, and low pressure during injection and sweep sub-steps to enable fast gas exchange. This dynamic adaptation of operating conditions resolves the contradiction between fast injection/sweep and fast reaction.
Solution Approach 2:
The system changes the pressure parameter dynamically throughout the ALD cycle. Specifically, pressure is increased during reaction sub-steps to enhance precursor flux and deposition rate, then decreased during injection and sweep sub-steps to improve gas exchange efficiency. This parameter modulation allows both fast injection/sweep and fast reaction to occur at different times.
2Productivity
If higher pressures are used during reaction sub-steps, then reaction speed increases, but injection and sweep sub-steps become slower
Solution Approach 1:
The patent implements periodic alternation between high-pressure reaction phases and low-pressure injection/sweep phases. This periodic switching allows the system to optimize for reaction speed during high-pressure periods and optimize for gas exchange speed during low-pressure periods, eliminating the need to choose one condition over the other permanently.
Solution Approach 2:
By making pressure a dynamic variable that changes periodically throughout the ALD cycle rather than maintaining a constant pressure, the system can achieve both fast reactions (during high-pressure periods) and fast injection/sweep (during low-pressure periods), resolving the time loss contradiction.
3Ease of operation
If higher gas flow rates are used, then sweep efficiency improves, but precursor waste increases
Solution Approach 1:
The patent changes the pressure parameter to control gas flow dynamics. By operating at low pressure during injection and sweep sub-steps, the system achieves efficient gas exchange with lower flow rates, reducing precursor waste while maintaining sweep efficiency. The low pressure enhances the effectiveness of each gas molecule in clearing the reaction chamber.
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 enables higher productivity, reduced precursor waste, and faster deposition rates at lower substrate temperatures, while allowing for larger process spaces and more efficient abatement of precursor gases, overcoming the limitations of conventional ALD systems.
Implementation Method 1
Gaede pump stages to modulate pressures and gas flow rates during ALD sub-steps, allowing for higher precursor pressures and lower flow rates during reaction sub-steps, and lower pressures and higher flow rates during sweep sub-steps
Implementation Method 2
Atomic layer deposition (ALD) provides highly conformal material coatings with exceptional quality, atomic layer control, and uniformity
Implementation Method 3
The substrate surface is typically prepared to include hydrogen-containing ligands AH (e.g., A=O, N, or S). These hydrogen-containing ligands react with the first precursor gas to deposit a layer of metal by the reaction: substrate−AH+MLx→substrate−AMLx-1+HL
Implementation Method 4
an inert-gas (e.g., N2 or Ar) sweep sub-step that acts to sweep substantially all of the remaining first precursor gas from the process space
Data Source
AI summary
A method of depositing a material on a substrate comprises placing a substrate into a process space in fluidic communication with a Gaede pump stage (GPS). A precursor gas is then injected into the process space while injecting a draw gas at a draw gas flow rate into the GPS such that the injected precursor gas achieves a precursor pressure and a precursor gas flow rate in the process space. Subsequently, substantially all of the precursor gas remaining in the process space is swept from the process space by injecting a sweep gas into the process space such that the injected sweep gas achieves a sweep pressure and sweep gas flow rate in the process space. The precursor pressure is higher than the sweep pressure, and the precursor gas flow rate is lower than the sweep gas flow rate.