Pressure-Charged Process Chamber for Fast Etchant Gas Pulsing
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Solution Overview
Problem
Existing processing chambers are unable to pulse etchant gases quickly enough to maintain high selectivity between oxide and nitride surfaces during semiconductor manufacturing, leading to decreased etch selectivity and potential leakage current issues.
Innovation Solution
The implementation of processing chambers with fast-switching valves and gas reservoirs connected to the lid, allowing for rapid charging and purging of etchant gases within the process volume, maintaining a constant high-level etchant flow for pulses less than or equal to 3 seconds, and utilizing a modified chamber design with heating capabilities and individual gas injection to prevent condensation and ensure precise control over the etching process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If existing processing chambers use conventional gas delivery systems, then the chamber can perform standard etching processes, but the etchant gas cannot be pulsed quickly enough to maintain high selectivity between oxide and nitride surfaces
Solution Approach 1:
The gas delivery system is segmented into separate reservoirs for different etchant gases (CF4, SF6, C4F8) connected to the process chamber through fast-switching valves. This segmentation allows independent control and rapid switching between different gas sources, enabling pulse durations of less than 3 seconds to maintain high SiO/SiN selectivity while preventing leakage current issues.
2Reliability
If the substrate is exposed to etchant gas for longer duration to ensure complete etching, then the etching process is more thorough, but the etch selectivity decreases and leakage current issues occur
Solution Approach 1:
The system implements periodic pulsing of etchant gases into the process chamber, with each pulse duration precisely controlled to be less than 3 seconds. Multiple pulses are delivered in sequence, allowing complete etching through cumulative effect while maintaining high selectivity by preventing continuous exposure that would cause leakage current and loss of SiN spacer integrity.
Solution Approach 2:
The gas delivery system incorporates flow sensors and pressure sensors that provide real-time feedback on gas flow rates and chamber pressure. This feedback enables precise control of pulse timing and duration, ensuring that etching is complete while maintaining the incubation delay period to preserve selectivity between SiO and SiN materials.
3Manufacturing precision
If fast-switching valves and gas reservoirs are added to enable rapid gas pulsing, then etch selectivity is maintained, but the device complexity increases
Solution Approach 1:
Etchant gases are pre-filled into separate reservoirs (CF4 reservoir, SF6 reservoir, C4F8 reservoir) before the etching process begins. This preliminary preparation allows the fast-switching valves to simply open pre-charged gas lines rather than managing complex real-time gas synthesis or storage, reducing operational complexity while enabling rapid pulsing with durations of less than 3 seconds to maintain high selectivity.
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 achieves high SiO/SiN selectivity, preserving the SiN spacer while etching SiO, reducing failure due to leakage current, and maintaining high etch selectivity by keeping the etching reaction within the incubation delay period.
Implementation Method 1
Each of the first gas reservoir and second gas reservoir has a volume sufficient to maintain a constant high level etchant flow to the process volume throughout a pulse less than or equal to 3 seconds
Implementation Method 2
The at least one etchant gas selectively etches a third material from the first material relative to the second material
Implementation Method 3
utilizing a modified chamber design with heating capabilities and individual gas injection to prevent condensation
Data Source
AI summary
Processing chambers including at least one gas reservoir connected to and in fluid communication with the lid through a fast-switching valve and a gas reservoir line are described. Processing methods, for example, etching methods, using the processing chambers are also described.