Plasma Gas Composition Analysis via Atomic Emission
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Solution Overview
Problem
Conventional spectroscopic techniques struggle to accurately analyze gas mixtures in semiconductor manufacturing processes, particularly in plasma etching, due to overlapping bands and the difficulty in identifying specific gas components, especially when dealing with small signals and unstable molecular fragments.
Innovation Solution
Delivering sufficient power to a plasma to dissociate molecules and molecular fragments into individual atoms, creating spectra that allow for the precise identification of chemical composition, including the detection of process endpoints by monitoring changes in atomic emission peaks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional spectroscopic techniques are used to measure gas composition in plasma chambers, then measurement can be performed with standard equipment, but the overlapping bands make it difficult to identify specific gas components and determine chemical composition accurately
Solution Approach 1:
The patent changes the energy parameter of the plasma by delivering sufficient power to dissociate molecules into atoms. This transforms the spectral characteristics from overlapping molecular bands to distinct atomic emission lines, enabling accurate gas composition identification. The energy input modifies the plasma state to optimize measurement conditions.
Solution Approach 2:
The patent uses plasma excitation (a form of energy vibration) to atomize the gas molecules. The high-energy plasma environment causes molecular dissociation and atomic excitation, producing characteristic emission spectra that are easier to analyze than molecular bands.
2Measurement precision
If sufficient power is delivered to plasma to dissociate molecules into atoms, then clear atomic emission spectra are produced for accurate identification, but energy consumption increases
Solution Approach 1:
The patent optimizes the power delivery parameter to achieve the minimum necessary energy input for complete molecular dissociation. By carefully controlling the energy parameter, the system transitions from molecular to atomic emission without excessive energy consumption, balancing measurement quality with energy efficiency.
3Productivity
If real-time metrology is performed in situ in the process chamber, then process monitoring can be done continuously, but the measurement capabilities are limited compared to ex situ methods
Solution Approach 1:
The patent uses the plasma itself as an intermediary medium for measurement. By analyzing the emission spectra from the process plasma, the system obtains real-time information about gas composition and process state without requiring physical access to the wafer surface, thus maintaining both real-time capability and measurement accuracy.
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 simplifies the identification of gas components and enables precise determination of process endpoints, such as the completion of silicon-containing dielectric etching, by producing clear and distinguishable atomic emission spectra, even in complex gas mixtures.
Implementation Method 1
Delivering sufficient power to a plasma to dissociate molecules and molecular fragments into individual atoms
Implementation Method 2
When these electrons fall back to their lower-energy states, photons, with energy equal to the energy lost by the electrons, are emitted from the gaseous particles. The energy of each of the photons is characteristic of the particle (atom, molecule, or molecular fragment) from which it was emitted.
Data Source
AI summary
Embodiments of the present invention relate to the analysis of the components of one or more gases, for example a gas mixture sampled from a semiconductor manufacturing process such as plasma etching or plasma enhanced chemical vapor deposition (PECVD). Particular embodiments provide sufficient power to a plasma of the sample, to dissociate a large number of the molecules and molecular fragments into individual atoms. With sufficient power (typically a power density of between 3-40 W/cm3) delivered into the plasma, most of the emission peaks result from emission of individual atoms, thereby creating spectra conducive to simplifying the identification of the chemical composition of the gases under investigation. Such accurate identification of components of the gas may allow for the precise determination of the stage of the process being performed, and in particular for detection of process endpoint.