Plasma Dose Measurement via Wall Probe and OES
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Solution Overview
Problem
The Faraday cup, used for measuring dopant doses in semiconductor manufacturing, faces accuracy issues due to deposit adhesion and abnormal discharges, and is ineffective for measuring electrically neutral particles like radicals in plasma doping techniques.
Innovation Solution
A plasma processing apparatus incorporating a wall probe to measure charged particle density and an Optical Emission Spectrometer (OES) to measure light emission intensity, with a calculation unit to determine dopant doses, allowing for accurate measurement of radical-containing dopants and enabling cleaning instructions based on threshold values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a Faraday cup is used to measure dopant dose in plasma doping, then charged particle measurement is enabled, but measurement accuracy deteriorates due to deposit adhesion on the electrode
Solution Approach 1:
The invention extracts the measurement function from the traditional Faraday cup electrode and implements it through a wall probe that measures plasma potential. This separates the measurement mechanism from the problematic tubular electrode structure that accumulates deposits, thereby maintaining measurement accuracy without the adhesion issue.
Solution Approach 2:
The invention introduces a wall probe as an intermediary measurement device that indirectly measures dopant dose through plasma potential and light emission intensity, rather than directly measuring current on an electrode. This intermediary approach avoids the deposit adhesion problem while still enabling dose measurement.
2Measurement precision
If a Faraday cup electrode is disposed within the processing chamber, then charged particle measurement is possible, but abnormal discharge occurs due to electric field concentration
Solution Approach 1:
The invention removes the Faraday cup electrode from the processing chamber environment and replaces it with a wall probe that measures plasma potential. This extraction eliminates the electric field concentration issue that causes abnormal discharge and metal scattering while preserving the measurement capability.
Solution Approach 2:
The invention replaces the mechanical/electrical measurement system (Faraday cup electrode measuring current) with a field-based measurement system (wall probe measuring plasma potential and OES measuring light emission). This substitution eliminates the harmful electric field concentration effects.
3Measurement precision
If a tubular electrode is installed within the processing chamber for dose measurement, then charged particle detection is enabled, but cleaning difficulty increases due to deposit adhesion
Solution Approach 1:
The invention extracts the measurement function from the tubular electrode and implements it through a wall probe. This eliminates the tubular structure that is difficult to clean, as the wall probe measures plasma potential without requiring a hollow electrode interior that accumulates deposits.
Solution Approach 2:
The wall probe serves as an intermediary that enables dose measurement without requiring a tubular electrode structure. By measuring plasma potential and light emission intensity, it achieves the same measurement goal without the cleaning difficulty associated with tubular electrodes.
4Measurement precision
If a Faraday cup is used for dopant measurement, then charged particle dose is measurable, but measurement of electrically neutral particles such as radicals becomes impossible
Solution Approach 1:
The invention creates a universal measurement system that can measure both charged particles (through plasma potential) and electrically neutral particles like radicals (through light emission intensity). The combination of wall probe and OES measurements enables versatile dopant dose measurement regardless of particle charge state.
Solution Approach 2:
The invention introduces light emission intensity measurement as an intermediary that enables detection of electrically neutral particles. By measuring the light emitted from excited species in the plasma, the system can detect radicals and other neutral particles that are invisible to traditional Faraday cup electrostatic measurement.
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 solution enables precise measurement of dopant doses including radicals, improves measurement accuracy, and reduces throughput limitations and discharge risks, while maintaining chamber cleanliness.
Implementation Method 1
a wall probe configured to measure a change in voltage corresponding to a density of charged particles in the plasma generated within the processing chamber
Implementation Method 2
an OES (Optical Emission Spectrometer) configured to measure a light emission intensity of the dopant existing in the plasma
Implementation Method 3
In the plasma doping technique, ions or radicals included in plasma serve as a dopant which acts on a semiconductor crystal
Data Source
AI summary
There is provided a plasma processing apparatus, which includes: a processing chamber into which a target substrate is loaded and in which a dopant is implanted into the target substrate using a plasma of a gas which contains an element used as the dopant; a wall probe configured to measure a change in voltage corresponding to a density of charged particles in the plasma generated within the processing chamber; an OES (Optical Emission Spectrometer) configured to measure a light emission intensity of the dopant existing in the plasma; and a calculation unit configured to calculate a dose amount of the dopant implanted into the target substrate, based on a measurement result obtained at the wall probe and a measurement result obtained at the OES.