Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J49/00—Particle spectrometers or separator tubes
  • H01J49/26—Mass spectrometers or separator tubes
  • H01J49/34—Dynamic spectrometers
  • H01J49/40—Time-of-flight spectrometers
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
  • H01J37/32—Gas-filled discharge tubes
  • H01J37/32009—Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources
  • H01J37/32422—Arrangement for selecting ions or species in the plasma
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
  • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
  • H01J37/02—Details
  • H01J37/244—Detectors; Associated components or circuits therefor
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
  • H01J37/32—Gas-filled discharge tubes
  • H01J37/32917—Plasma diagnostics
  • H01J37/32935—Monitoring and controlling tubes by information coming from the object and/or discharge

Definitions

• Plasma processes are widely used in semiconductor manufacturing, for example, to implant wafers with various dopants, to deposit or to etch thin films.
• PLAD plasma doping
• ion composition of a plasma may be a critical piece of information that determines dopant species, dopant depth profiles, process-related contamination, etc.
• the ion composition changes with PLAD process parameters such as gas ratio, total gas pressure, and discharge power.
• the ion composition can also change significantly depending on the conditioning status of a plasma chamber. Therefore, it is important to know the ion composition during a PLAD process, preferably in situ and in real-time, in order to achieve repeatable and predictable process results.
• conventional ion sensors such as commercial mass/energy analyzers and quadrapole mass spectrometers
• Large ion sensors tend to perturb a plasma under measurement and therefore distort the process results.
• the size and weight of conventional ion sensors often limit their deployment options in a semiconductor process tool.
• time-resoived measurements of the plasma are often required.
• few existing ion sensors provide the capability of time-resolved measurements.
• Figure 1 shows an exemplary ion sensor in accordance with an embodiment of the present disclosure.
• Figure 2 shows an ion sensor having one exemplary configuration in accordance with an embodiment of the present disclosure.
• Figure 2a shows an ion sensor having an energy analyzer in accordance with an embodiment of the present disclosure.
• Figure 3 shows an ion sensor having another exemplary configuration in accordance with an embodiment of the present disclosure.
• Figure 4 shows an ion sensor having yet another exemplary configuration in accordance with an embodiment of the present disclosure.
• Figure 5 shows one installation option for an ion sensor in accordance with an embodiment of the present disclosure.
• Figure 6 shows another installation option for an ion sensor in accordance with an embodiment of the present disclosure.
• FIG. 6a-c show different examples of plasma processing chambers in accordance with embodiments of the present disclosure.
• Figure 7 shows yet another installation option for an ion sensor in accordance with an embodiment of the present disclosure.
• Figures 7a-b show exemplary systems for employing ion sensors for process control in accordance with embodiments of the present disclosure.
• Figure 8 shows an exemplary ion sensor in accordance with an embodiment of the present disclosure. Detailed Description
• Embodiments of the present disclosure provide a number of compact designs of time-of-flight (TOF) ion sensors that are suitable for ⁇ n-situ monitoring and controlling of a plasma process. These designs may employ flexible ion extraction and ion focusing techniques to measure ion composition in a plasma chamber.
• TOF ion sensor may be installed in a variety of ways in the plasma chamber and may be configured for a number of functions such as, for example, in-situ process control, chamber readiness verification, fault detection, implant dose correction, and implant uniformity measurement.
• the sensitivity and size of each ion sensor may allow time-resolved measurement and spatial measurement of a plasma.
• the ion sensor 100 includes an ionization source 101 that generates ions proximate to the entrance of the ion sensor 100.
• the ion source 101 generates an electron cloud using a low energy electron source. The electrons in the electron cloud cause electron impact that facilitates the ionization of neutral atoms and molecules and the conversion of ions by electron attachment.
• the ion source 101 generates ions proximate to the entrance of the ion sensor 100 by ion-impact and/or by photon-impact ionization.
• the ion source 101 can be a continuous or a pulsed ion source. The ion source 101 is useful for some applications where it is desirable to provide conventional RGA type measurements of the neutral gas or fast neutral species.
• Ion sensor 100 comprises a housing 102 that may be adapted for installation in a view port of a plasma chamber and that may accommodate differential pumping.
• the housing 102 may be individually biased at a desired potential Visi ng -
• a left hand side of the housing 102 may be referred to as an "extractor side” since ions extracted from a plasma enter the ion sensor 100 via an aperture ("housing aperture") on the left hand side of the housing 102.
• a right hand side of the housing 102 may be referred to as a "detector side” since ion detection takes place on the right hand side of the housing 102.
• the ion sensor 100 includes a drift tube 104 inside the housing 102 which may also be individually biased, for example, at a desired potential Vo-
• the drift tube 104 typically has a hollow space with a negligible electromagnetic field.
• An extractor side of the drift tube 104 may have an aperture ("drift tube aperture") for admitting ions.
• a detector side of the drift tube 104 may have a grid 124 that allows ions to exit while shielding out external electric fields.
• the plasma chamber's pressure is typically 1-3,000 mTorr, while the drift tube pressure is typically at 2x10 " ⁇ Torr or less. Differential pumping can be used to maintain the pressure difference.
• Various embodiments include one or more electrodes and/or grids that form lenses or deflectors proximate to the extractor side of the drift tube 104, between the housing aperture and the drift tube aperture.
• the extractor electrode 106 may have an aperture that is between 10 and 500 microns in diameter (preferable 50-200 microns for some embodiments), although the actual aperture size may vary, at least in part, on the differential pumping requirements.
• the extractor electrode 106 may be biased at a suitable potential V ex tractor in. order to attract either positive or negative ions from a plasma.
• the attracted ions may be traveling at diverse angles.
• two or more electrodes e.g., electrostatic lenses 108 and 110
• Each electrostatic lens may be individually biased to create a desired electrostatic field that directs the ions in a focused beam.
• the electrostatic lenses are biased with either a positive or a negative voltage.
• One of the electrostatic lenses may be provided with a voltage pulse to admit a portion (or packet) of the attracted ions into the drift tube 104. The voltage pulse may be repeated in a timed manner for a periodical or near-continuous sampling of the ions.
• a combination of a repeller voltage and an extraction voltage pulse is applied to any pair of electrodes to drives positive ions into the drift tube 104.
• the flight time of the ions is determined relative to the time at which the extraction pulse occurs.
• the electrostatic lens 108 is biased with a positive voltage pulse V L1 .
• the positive voltage pulse can be periodic or non-periodic.
• the electrostatic lens 110 is biased at a positive repelling voltage V L2 .
• a positive repeller voltage is applied to electrostatic lens 110 and a positive voltage pulse is applied to the nearby electrostatic lens 108 in order to drive positive ions past the repeller electrodes and into the drift tube 104.
• the positive repeller voltage may be periodic or not.
• the drift tube 104 when biased at V L3 , may function as a third electrostatic lens in the series.
• the bias voltage on the drift tube may be a pulsed voltage. Negative ions may be extracted into the drift tube using a similar arrangement.
• voltage pulses are applied to more than one of the electrodes.
• voltage pulses can be applied to at least two of the drift tube 104, the extractor 106, the electrostatic lens 108, and the electrostatic lens 110.
• the at least two voltage pulses can be applied either simultaneously or delayed by a predetermined time in order to cause ions to enter the drift tube.
• a blocking voltage is applied to at least one of the extractor
• the magnitude of the blocking voltage is periodically varied in order to allow some ions to enter the drift tube.
• the flight time of the ions through the drift tube 104 is determined relative to the time at which this voltage is changed.
• the ions drift towards the detector end virtually unaffected by any electric field.
• the ions typically have the same kinetic energy. Heavy ions travel relatively slow and light ions travel relatively fast. Given a sufficient flight time (i.e., sufficient length of the drift tube 104), the ions become separated into individual packets based on ion mass of their ionic species.
• the transmission of ions (positive or negative) through the drift tube is modulated using an arrangement of quadrupole elements.
• the modulation is periodic.
• the modulation is non-periodic. Modulation may be accomplished by varying the RF or DC voltages associated with the individual quadrupole elements.
• the flight time of the ions is determined relative to the time at which the modulation occurs.
• the transmission of ions (positive or negative) through the drift tube can be modulated by numerous other means.
• the transmission of ions can be modulated by electrostatic deflection of the ions.
• the transmission of ions can also be modulated by a mechanical means such as a mechanical gating, multi-stage chopper, or any other type of mechanical interrupter.
• the mechanical interrupter is a mechanical shutter. Modulation by mechanical means is sometimes advantageous for low energy applications.
• the flight time of the ions is also determined relative to the time at which the modulation occurs.
• a detector assembly 112 may be used to detect the ions.
• the detector assembly 112 may be any type of commercially available or customized ion detection device (e.g., micro-channel plate (MCP) assembly). Detection and/or collection of the ions may be controlled, for example, with one or more voltage biases such as V MCP -
• the detector assembly 112 may be coupled to a pre-amplifier 118 that is in turn coupled to a processor unit 122 via an electronic interface 120.
• the electronic interface 120 may be, for example, a fast data acquisition card.
• the processor unit 122 may be, for example, a personal computer (PC) or an industrial type of computing device.
• the individual ion packets having distinct ion mass numbers are detected sequentially by the detector.
• the detected signals are amplified by the pre-amplifier 118.
• the amplified signals are then processed by the processor unit 122. Signals corresponding to each individual packet produce a mass peak in a mass spectrum.
• the mass spectrum accurately reflects an ion composition of the plasma based on one or more samplings of ion species from the plasma.
• the detector assembly 112 includes position-sensitive particle detectors that are used to detect the ions at certain predetermined positions. These position-sensitive particle detectors provide ion positional information that can be used to determine ion mass or ion energy.
• the portion of the detector surface used to detect ions is selected by electrical, magnetic, or mechanical means.
• an electrically addressable detector array can be used to detect ions as a function of position.
• a software algorithm can be used to extract the position-sensitive data from the detector signals.
• mechanical means can be used to control the effective divergence of the ions impacting the detector. For example, a mechanical barrier can be used to shield a portion of the detector.
• ion deflectors or ion collimators can be used to deflect or to collimate the ions so that they only impact a desired portion of the detector.
• the ion sensor 100 may be flexibly configured by applying different combinations of voltage potentials to the housing 102, the drift tube 104, the extractor electrode 106, the electrostatic lenses 108 and 110, and the detector assembly 112. Exemplary configurations are shown in Figures 2-4.
• Figure 2 shows an ion sensor 200 having one exemplary configuration in accordance with an embodiment of the present disclosure.
• the ion sensor 200 may comprise substantially the same components as the ion sensor 100 shown in Figure 1.
• the housing 104 may be grounded and/or attached to a plasma chamber wall.
• the extractor electrode 106 is biased at a DC extractor voltage Vextractor- "50V — OV DC for extraction of positive ions or V exlra ctor ⁇ OV — 50V DC for extraction of negative ions.
• a pulsed voltage or RF signal is applied to the extractor electrode 106 to attract or repel ions.
• the extractor electrode 106 is electrically floating.
• the pulsed voltage is periodic or non- periodic and the RF signal is pulsed or CW. The pulsed and RF voltage signals may be used to enable desorption from or deposition on the electrode surface.
• the description below will assume that only positive ions are sampled. It should be noted, however, that embodiments of the present disclosure can be easily adapted or configured for sampling of negative ions.
• the electrostatic lens 108 is referred to as Lens 1
• the electrostatic lens 110 is referred to as Lens 2
• the drift tube 104 is referred to as Lens 3.
• Lens 1 and Lens 3 may be held at a same or similar potential which may be a fixed value between, for example, -150V and -300V.
• the desired potential is determined by factors, such as the length of the drift tube 104 and the desired ion mass resolution.
• Lens 1 and Lens 3 may be biased at different potentials
• Lens 2 may be further configured as a "gate" for the drift tube 104.
• a short voltage pulse e.g., 50-500 nanosecond
• Lens 2 may be normally biased with a positive voltage, e.g. +30V or above, except during the very short gating period.
• the gate pulse width is 100 ns
• the gate pulse When the gate pulse is synchronized with the wafer pulse, a delay may be introduced to control where the gate pulse is open relative to the wafer pulse. In this way, it is possible to sample the plasma at different points in time space with a high resolution.
• the collective effect of the biases on Lenses 1-3 may be an electrostatic field that focuses the admitted ions into a beam with a limited divergence angle.
• the detector assembly 112 On the detector side, the detector assembly 112 may be biased at a high voltage V MCP -
• the grid 124 may electrostatically shield the drift tube 104 from the high voltage V MCP -
• the ion sensor 200 may also be configured for time-resolved measurements of a plasma.
• Many semiconductor processing plasmas are "pulsed plasmas" which alternate between on and off (afterglow) states periodically.
• the plasma-on state may last 1-50% (or higher) of each cycle.
• the pulsed operation can cause dynamic changes in plasma conditions and process chemistries.
• the sampling of the ion species may be synchronized with either the plasma pulses or wafer bias pulse, or both if they are synchronized. By changing the gate delay relative to the reference pulse (plasma pulses and/or wafer bias), time-resolved measurement could be carried out over the whole period.
• the flight times of the ions are determined by observing the time difference between a start signal and a stop signal.
• the ion modulation event (an electrical or mechanical event) is initiated by the start signal.
• the stop signal is determined by the arrival time of the ions at the ion detector.
• start and stop signals are used to gate a pulse train of known frequency to give a count that is proportional to the flight time.
• the start and stop signals are used to generate a voltage across a capacitor, which is then discharged at a constant rate. The discharge period is used to gate a pulse train to give an count that is proportional to the flight time.
• the start and stop signals are used to enable the generation of an analog pulse whose magnitude is proportional to the flight time.
• the ion sensor 200 may also be configured to measure the energy distribution of the ions and/or the plasma potential.
• an electrode or grid such as the extractor electrode 106, the electrostatic lens 108, and the electrostatic lens 110 is biased to be a retarding element. The number of ions transmitted as a function of the electrode voltage is then measured. Both the energy distribution and the plasma potential can be determined from the measured data.
• the energy distribution of the ions is determined by observing the spread in the arrival times of the ions at the detector assembly 122.
• position-sensitive particle detectors can be used to detect the ions at certain predetermined positions as described in connection with Figure 1.
• the energy distribution can be measured directly by methods that are well known in the art.
• calibrated particle detectors can be used to measure energy or mass by observing the amplitude of signals generated by the detectors.
• the drift tube 104 is configured to perform the function of an energy analyzer. There are numerous ways to configure the drift tube 104 as an energy analyzer.
• the drift tube 104 is formed in a curved shape and includes electrostatic or magnetic deflection elements.
• the shape of the drift tube 104 is chosen so that ions with different energies bend with different angles.
• the drift tube 104 includes a parallel-plate energy analyzer as part of the drift path to the detector assembly 112.
• the energy analyzer can be a 45 degree type energy analyzer.
• the drift tube 104 includes a cylindrical mirror or a spherical energy analyzer as part of the drift path to the detector assembly 112.
• one or more grids are placed in the ion path to configure the drift tube 104 as a retarding potential analyzer.
• the drift tube can include a RF quad ⁇ ipole or one or more permanent or electro-magnets with the ability to differentiate between ions of different energies by adjusting the RF or DC voltages.
• the positions of the permanent magnets can be adjustable.
• FIG. 2a shows an ion sensor 200A having an energy analyzer 114 in accordance with an embodiment of the present disclosure.
• the energy analyzer 114 is positioned between the drift tube 104 and the detector assembly 112.
• the energy analyzer 114 can be usedto select ions within a desired energy range.
• FIG 3 shows an ion sensor 300 having another exemplary configuration in accordance with an embodiment of the present disclosure.
• the ion sensor 300 may comprise substantially the same components as the ion sensor 100 shown in Figure 1.
• the extractor electrode 106 receives a RF (1-300!MHz, typically 13.56MHz) bias.
• the RF biased extractor electrode 106 may serve dual functions. That is, the extractor electrode 106 may extract ions and also may remove deposits from the extractor aperture in a deposition-dominant environment.
• a RF bias may help sputter clean the extractor aperture to remove the deposited materials.
• a RF bias may provide the ion sensor 300 with a "self-cleaning" capability.
• the RF bias may have a negative average potential (or RF self- bias) between -50V and OV, and a peak-to-peak value of OV-100V.
• the RF self-bias may be larger than a sputtering threshold and the peak-to-peak value may be 100-lOOOV or higher.
• Figure 4 shows an ion sensor 400 having yet another exemplary configuration in accordance with an embodiment of the present disclosure.
• the ion sensor 400 may comprise substantially the same components as the ion sensor 100 shown in Figure 1. However, in this exemplary configuration the extractor electrode 106 also functions as a gate. A gate pulse may be provided to the extractor electrode 106 to pull a packet of ions into the ion sensor 400. Lens 2 may be provided with a DC bias to focus the ion beam.
• Ion sensors in accordance with embodiments of the present disclosure may be installed in a number of ways for flexible detection of ion species in a plasma chamber. Exemplary installation options are shown in Figures 5-7.
• FIG. 5 shows one installation option for an ion sensor 508 in accordance with an embodiment of the present disclosure.
• An over-simplified plasma chamber 500 is shown with a platen/cathode 502 holding a wafer 504.
• An anode 506 is positioned above the platen/cathode 502.
• the anode 506 is not necessarily grounded but may be biased at a voltage, for example, that is between -1 fcV and +1 kV (other voltages are possible).
• An anode shaft 507 may enable movement of the anode 506 in the vertical direction.
• a plasma 50 may be generated between the anode 506 and the platen/cathode 502, either by cathode bias voltages or by additional plasma sources.
• negative voltage pulses may be applied to the platen 502 to draw positive ions towards the wafer 504.
• positive voltage pulses may be used.
• the ion sensor 508 may be installed in a sidewall of the plasma chamber 500. The installation may be through a view port or similar mechanism.
• the ion sensor 508 may have its extractor tip extended sideway into or near an edge of the plasma 50.
• the extractor tip may be positioned on a movable mount. Due to the small size of the extractor tip, it may be inserted deep into the plasma 50 without significantly disturbing the plasma 50.
• FIG. 6 shows another installation option for an ion sensor in accordance with an embodiment of the present disclosure.
• an ion sensor 602 may be installed on the anode side. That is, the ion sensor 602 may be positioned through the anode 506 and may be vertically oriented with its extractor tip pointing downwards at or into the plasma 50. The ion sensor 602 may be electrically connected with the anode 506. The ion sensor 602 or its extractor tip may move up and down independent from the anode 506 to sample ions at different spatial points in the plasma chamber 500.
• the ion sensor 602 or its extractor tip may move up and down together with the anode 506 for in-situ diagnostic of different process conditions.
• the horizontally positioned ion sensor 508 maybe similarly actuated for a spatial measurement of the plasma 50.
• FIGS 6a-c show different examples of plasma processing chambers in accordance with embodiments of the present disclosure.
• FIG. 6a there is shown a plasma chamber 600A.
• An ion sensor 602 may be installed through an anode 506.
• a bellows seal 604 may accommodate installation and movement of the ion sensor 602 through the chamber wall.
• the plasma 50 may be generated by negatively pulsed voltages applied on the wafer 504 or the platen 502. According to one embodiment, extraction of ions from the plasma 50 into the ion sensor 602 may be synchronized with the plasma generation, and therefore the voltage pulses on the wafer 504.
• FIG. 6b there is shown a plasma chamber 600B.
• the plasma generation technique shown in Figure 6b is different from the plasma generation technique shown in Figure 6a.
• the plasma chamber 600B may have one or more external plasma sources, such as, for example, ICP or Helicon plasma sources.
• a RF power supply 605 and a RF matching unit 607 is coupled to RF coils 606.
• the RF coils 606 may supply RF electrical power into the plasma chamber 600B.
• the platen 502 may be biased to control the energy of ions that impact the wafer 504.
• a plasma chamber 600C wherein another plasma generation technique is employed.
• One or more microwave sources may be coupled to the plasma chamber 600C to supply the power to generate and sustain the plasma 50.
• a microwave supply 611 may be coupled to a microwave cavity 608 via a tuner 613 and a waveguide or cable.
• the microwave power supplied to the microwave cavity 608 may generate a "source plasma" therein, whereupon the source plasma may diffuse into the plasma chamber 600C to produce the plasma 50.
• the plasma 50 may be generated directly inside the plasma chamber 600C by coupling microwave power via the cavity 608 and into the plasma chamber 600C.
• FIG. 7 shows yet another installation option for an ion sensor in accordance with an embodiment of the present disclosure.
• one or more ion sensors 702 may be installed on the cathode side. That is, an ion sensor 702 may be positioned vertically through the platen/cathode 502 with the extractor tip positioned next to the wafer 504.
• the installation location for the ion sensor 702 may be (or near) where a Faraday cup would be typically located. Since the extractor tip is pointing up at the plasma 50, the ion sensor 702 and the wafer 504 may share a same or similar vantage point with respect to the plasma 50.
• the ion sensor 702 may "see" the same composition and dose of ions as what the wafer 504 sees, which may facilitate a more accurate control of plasma processing of the wafer 504.
• the ion sensor 702 may be able to directly detect what ions are implanted into the wafer 504. If desired, the ion sensor 702 may also be moved up and down for a spatial measurement.
• Figures 7a-b show exemplary systems for employing ion sensors for process control in accordance with embodiments of the present disclosure.
• Figure 7a shows an ion sensor 702 being installed next to the wafer 504.
• Faraday cup 704 may be installed on the other side of the wafer 504 or the Faraday cup 704 may partially surround the wafer 504. Both the ion sensor 702 and the Faraday cup 704 face up to a plasma (not shown) as the wafer 504.
• the ion sensor 702 may be coupled to a unit 706 that calculates an in-situ ion composition based on detection data received from the ion sensor 702.
• the Faraday cup 704 may be coupled to a charge counter 708 that calculates a total ion dose based on the Faraday cup current.
• the ion composition information and the ion dose data may be input to a dose correction module 710. In addition, the ion composition data may be input to a system controller 712 for further process control.
• Figure 7b shows two or more ion sensors 702 being installed around the wafer
• the in-situ ion composition data from these ion sensors 702 may be input to the system controller 712.
• Output functions 714 of the system controller 712 may include, but are not limited to, ion dose correction, dose uniformity control, plasma chamber conditioning, and/or process fault detection.
• the drift tube 104 ( Figure 1) may either be isolated from the platen or be at the platen potential.
• the ion sensor For the cathode-side (or wafer-side) measurement of the plasma 50, the ion sensor
• FIG 8 shows an exemplary ion sensor 800 in accordance with an embodiment of the present disclosure.
• the ion sensor 800 may comprise substantially the same components as the ion sensor 200 shown in Figure 2, except that the extractor electrode 106 is removed.
• the housing aperture at the extractor side may be shrunk to approximately 10-500 microns (preferably 50-200 microns).
• the housing 102 may be biased at a same or similar potential (e.g.,
• Lens 1 (drift tube 104), and detector assembly 112 may also be biased at a same or similar potential.
• Lens 2 may function as a gate to pulse ion packets into the drift tube 104.
• this input data processing and output data generation may be implemented in hardware or software.
• specific electronic components may be employed in a plasma processing tool or similar or related circuitry for implementing the functions associated with in-situ monitoring of ion species in accordance with the present disclosure as described above.
• one or more processors operating in accordance with stored instructions may implement the functions associated with in-situ monitoring of ion species in accordance with the present disclosure as described above. If such is the case, it is within the scope of the present disclosure that such instructions may be stored on one or more processor readable carriers (e.g., a magnetic disk), or transmitted to one or more processors via one or more signals.
• processor readable carriers e.g., a magnetic disk
• the dose or plasma conditions may be changed as part of an automated or semi-automated closed control loop that includes a controller or computer and electronic instrumentation that is responsive to data obtained from TOF sensor according to the present invention.
• the Data obtained from the detector assembly 112 can include the absolute or relative magnitudes of various portions of the measured TOF spectra.
• the data from the detector assembly 112 can also include the shape of the time-of-flight peaks, such as changes in FWHM.
• the data from the detector assembly 112 can also include the presence or absence of minor (contaminant) peaks, the energy distribution, and the mass distribution.
• the data from the TOF sensor can be used to detect fault conditions, such as gas impurities, residual contaminants, and malfunctions of equipment used to control the plasma.
• the plasma conditions can be changed in response to the data by adjusting the TOF sensor's operating parameters, such as gas flow, gas mixture, pressure, RF power, RF frequency, implant voltage, duty cycle, or other plasma related parameter.

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• 2007
  • 2007-02-23 US US11/678,524 patent/US7453059B2/en not_active Expired - Fee Related
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