Real-time radical output monitoring using optical emission spectroscopy.

Abstract

A system for determining the concentration of radicals in a particle stream delivered into a semiconductor processing chamber comprises a plasma generator, a spectrometer optically coupled to the glow discharge region of the plasma generator, and a controller communicatively coupled to the spectrometer. The plasma source is operable to generate a glow discharge to excite radicals and diluent gases in the accepted effluent stream. The spectrometer is operable to output measurement data representing the intensity of light emitted by the excited radicals and diluent gases. The controller is operable to calculate the concentration of radicals in the effluent stream based on the measurement data.

Description

Technical Field

[0001] background Embodiments of the present invention generally relate to an optical emission spectroscopy (OES) radical detection system and a method for radical detection using optical emission spectroscopy. More specifically, embodiments of the present invention relate to measuring the concentration of radical species in the effluent flow of a remote plasma source used in plasma-assisted semiconductor manufacturing processes, such as plasma enhanced atomic layer deposition (PEALD), plasma enhanced chemical vapor deposition (PECVD), or plasma etching.

Background Art

[0002] In semiconductor manufacturing processes, a plasma source can be used to generate particles that can be used to facilitate etching and deposition processes and to clean the inner surfaces of semiconductor processing chambers. Radicals are often important components in particle flows because they are highly reactive due to unpaired electrons. Remote plasma sources are often used to generate radical-containing particle flows at locations remote from the semiconductor processing chamber. However, radicals may be destroyed while being transported to the semiconductor processing chamber. For example, a remote plasma source can generate atomic fluorine radicals by dissociating NF3 molecules (i.e., NF3 → N + 3F), but the fluorine radicals may recombine to molecular fluorine via gas-phase and surface reactions (e.g., F + F → F2). Therefore, it may be desirable to measure the concentration of radicals in the particle effluent flow generated by a remote plasma source and adjust the operation of the remote plasma source and / or other components of the semiconductor processing system to correct or compensate for the destruction of radicals generated by the remote plasma source.

[0003] One known method for measuring radicals in particle streams is calorimetry, which measures the amount of thermal energy released as a result of radicals recombining into stable molecules. However, this method is unsuitable for use in semiconductor processing because it inevitably leads to the destruction (recombination) of the radicals being measured. The same applies to other known measurement methods such as etching rate measurement and chemical titration. While it is possible to divert a small portion of the effluent and apply the above methods only to the diverted flow, the resulting measurements may have reduced sensitivity due to the small sample size. In light of the above, there is a need for robust and efficient systems and methods for detecting radical concentrations in particle streams generated for semiconductor processing. [Overview of the project]

[0004] overview Embodiments of the present invention were devised and developed with the aim of providing solutions to the above-mentioned objective technical needs, as will be demonstrated in the following description.

[0005] One embodiment can be broadly characterized as a system for determining the concentration of radicals in a particle stream delivered into a semiconductor processing chamber, the system comprising: a plasma generator having an inlet configured to receive an outflow of a particle stream containing radicals and diluent gases, the plasma source being operable to generate a glow discharge for exciting radicals and diluent gases in the received outflow; a spectrometer optically coupled to the internal glow discharge region of the plasma generator and operable to output measurement data representing the intensity of light emitted by the radicals and diluent gases; and a controller communicatively coupled to the spectrometer and operable to calculate the concentration of radicals in the outflow based on the measurement data.

[0006] Another embodiment can be generally characterized as a particle flow delivery system used in conjunction with a semiconductor processing chamber, the system comprising: a remote plasma source operable to generate an outflow of particles containing radicals and diluent gases; a plasma generator having an inlet configured to receive the outflow and an outlet configured to be coupled to a semiconductor processing chamber, wherein the plasma source is operable to generate a glow discharge for exciting radicals and diluent gases in the outflow and to deliver the outflow to a semiconductor processing chamber; a light-shielding feature positioned between the remote plasma source and the plasma generator, the light-shielding feature being configured to deliver the outflow but to prevent light emitted from the remote plasma source from reaching the plasma generator; a spectrometer optically coupled to an internal glow discharge region of the plasma source and operable to output measurement data representing the intensity of light emitted by radicals and diluent gases; and a controller communicatively coupled to the spectrometer and operable to calculate the concentration of radicals in the outflow based on the measurement data. [Brief explanation of the drawing]

[0007] Brief explanation of the drawing The above and other aspects, features and advantages of the present invention will become more apparent from the following description, which is presented in conjunction with the drawings.

[0008] [Figure 1-2] Figures 1 and 2 are schematic diagrams showing OES radical detection systems according to several embodiments of the present invention.

[0009] [Figure 3] Figure 3 is a schematic diagram showing a specific component of the OES radical detection system shown in Figures 1 and 2.

[0010] [Figure 4] Figure 4 is a schematic diagram showing one embodiment of the spectrometer shown in Figures 1 and 2.

[0011] [Figure 5] Figure 5 is a chart comparing the results of the radical concentration determination method according to embodiments of the present invention, measured at various pressures, with the etching rate measured as a function of pressure. [Modes for carrying out the invention]

[0012] Detailed explanation Exemplary embodiments are described below with reference to the accompanying drawings. Unless otherwise explicitly stated, the sizes, positions, etc., of components, features, elements, etc., and the distances between them in the drawings are not necessarily to a constant scale and may be biased and / or exaggerated for clarity.

[0013] The terminology used herein is for the purpose of describing specific exemplary embodiments and is not intended to limit them. Where used herein, the singular form ("a", "an", and "the") is intended to include the plural form unless the context otherwise explicitly indicates. Where used herein, the term "comprises" and / or "comprising" specifies the presence of the described features, integers, steps, actions, elements, and / or components, but it should be recognized that this does not exclude the presence or addition of one or more other features, integers, steps, actions, elements, components, and / or groups thereof. Unless otherwise specified, ranges of values, when enumerated, include both the upper and lower bounds of the range, as well as any subranges between them. Unless otherwise specified, terms such as "first," "second," etc., are used solely to distinguish one element from another. For example, one node may be called the "first mirror," and similarly another node may be called the "second mirror," and vice versa.

[0014] Unless otherwise specified, terms such as “approximately” and “around that value” mean that quantities, sizes, formulas, parameters, and other quantities and characteristics may be approximate and / or greater or less than, if desired, taking into account tolerances, conversion factors, rounding, measurement errors, and other factors known to those skilled in the art.

[0015] Many of the embodiments described below share common components, devices, and / or elements. Components and elements with similar names refer to elements with similar names throughout. For example, many of the embodiments described in the detailed description below include at least one ultrapure water source (hereinafter, UPW source), carrier gas source, ammonia gas source, main flow channel, bypass flow channel, etc. Therefore, components or features with the same or similar names may be described by reference to other drawings even if they are not mentioned or described in the corresponding drawings. Similarly, elements not indicated by reference numerals may also be described by reference to other drawings.

[0016] Since many different forms and embodiments are possible without departing from the spirit and teachings of this disclosure, this disclosure should not be construed as being limited to the exemplary embodiments described herein. Rather, these exemplary embodiments are provided to make this disclosure sufficient and complete and to communicate the scope of this disclosure to those skilled in the art.

[0017] Remote plasma sources (RPS) are used to generate excited free radicals such as F, O, H, N, etc. for semiconductor processing. By using a non-invasive in-situ method to measure the radical density in the effluent stream of the RPS, semiconductor processes such as deposition or etching can be monitored, and ultimately, real-time feedback can be provided to the RPS for closed-loop process control. To overcome the limitations associated with conventional methods for measuring the radical yield of the RPS as described above, embodiments of the present invention employ the use of optical emission spectroscopy (OES), more specifically, photometry, to measure the radical concentration in the effluent stream of the RPS.

[0018] An exemplary configuration of an OES radical detection system (i.e., an OES photometry system) according to an embodiment of the present invention is schematically shown in FIGS. 1 and 2. Generally, the OES photometry system 100 shown in FIG. 1 and the OES photometry system 200 shown in FIG. 2 can be characterized as including a spectrometer 102 optically coupled to a plasma generator 106 (e.g., via a viewport 104), a light-shielding feature 108, and a system controller 112. FIGS. 1 and 2 also show an RPS 110 and a semiconductor processing chamber 114.

[0019] Although not shown, the RPS 110 can be fluidly connected to one or more precursor sources containing a composition that forms a plasma containing one or more radicals (e.g., F, O, H, N, etc.) as known in the art. Also, although not shown, the RPS 110 can be fluidly connected to one or more sources of dilution gas (e.g., Ar, He, N2, etc.) used, for example, to assist in the transport of radicals in the effluent stream as known in the art. Although only one RPS 110 and one OES photometry system are shown in FIGS. 1 and 2, it will be understood that a plurality of RPS 110 can be provided and fluidly connected to the same OES photometry system 100 or 200 (e.g., at the light-shielding feature 108).

[0020] The light-shielding feature portion 108 is coupled to the output portion of the RPS 110 (e.g., by one or more pipes, conduits, etc.) to receive radicals and dilution gas in the effluent stream generated by the RPS 110 (as shown by 101 for example). The light-shielding feature portion 108 is configured to allow radicals and dilution gas in the effluent stream to pass through the light-shielding feature portion 108 (as shown by 103 for example) while absorbing, attenuating, blocking light, or otherwise blocking the light emitted from the plasma generated inside the RPS 110. By blocking the emission of light from the RPS 110, the light-shielding feature portion 108 obstructs the direct viewing path between the output portion of the RPS 110 and the spectrometer 102 and helps to minimize the interference of the optical signal used to measure the radical concentration in the effluent stream of the RPS 110.

[0021] Examples of the light-shielding feature portion 108 include, but are not limited to, bends, baffles, screens, etc., or any combination thereof. For example, the light-shielding feature portion 108 can be provided as the bend 300 shown in FIG. 3. The bend 300 can be provided, for example, as a block or body that defines a channel extending therethrough. In the illustrated embodiment, the channel has two bends of, for example, 90 degrees, but each bend can be at any suitable angle. Although the channel is illustrated as having two bends, it will be understood that the channel can have a single bend or three or more bends. In the exemplary embodiment shown in FIG. 3, the channel of the bend 300 is fluidly coupled to the output portion of the RPS 110 by a conduit 302. Thus, radicals in the effluent stream generated by the RPS 110 can be conveyed to the double-bend block 300 via the conduit 302.

[0022] Referring again to Figures 1 and 2, the inlet of the plasma generator 106 is fluidically coupled to the light-shielding feature section 108 (e.g., by one or more pipes, conduits, etc.) to receive the effluent that has passed through it (e.g., as shown in 103). The plasma generator 106 can be operated to excite radicals and diluent gases in the received effluent so that they emit light by generating a glow discharge (e.g., within its glow discharge region). In particular, the plasma generator 106 is configured to excite radicals and diluent gases so that they emit photons and produce an optical signal strong enough to be detected by the spectrometer 102. However, it should be understood that the excitation should not be so strong that it chemically alters (e.g., dissociation, recombination, reaction, etc.) the components of the effluent (including radicals) (or chemically alters the components of the effluent in a way that would have an undesirable effect on the processing carried out in the semiconductor processing chamber 114). Therefore, the power of the plasma generator 106 can be relatively low (e.g., a few milliwatts to tens of watts). The plasma generator 106 can be provided as a capacitively coupled (CCP) plasma source, an inductively coupled (ICP) plasma source, a pulsed DC plasma source, a microwave plasma source, or the like.

[0023] In the exemplary embodiment shown in Figure 3, the input section of the plasma generator 106 is coupled to the channel of the bend 300 by the conduit 304. Thus, radicals and diluent gases in the outflow stream generated by the RPS 110 can be transported from the bend 300 to the plasma generator 106 via the conduit 304.

[0024] Referring again to Figures 1 and 2, the plasma generator 106 is further configured to allow radicals and diluent gases in the outflow to pass through the plasma generator 106 (for example, for distribution into the semiconductor processing chamber 114). In one embodiment, the plasma generator 106 may be provided as a CLEANLINE model KF40, a foreline plasma clean system manufactured by MKS INSTRUMENTS. For example, in the embodiment shown in Figure 1, the plasma generator 106 is located outside the semiconductor processing chamber 114, and the outlet of the plasma generator 106 is fluidically coupled to the semiconductor processing chamber 114 (for example, by one or more pipes, conduits, etc., as known in the art) to allow gases in the outflow to pass from the plasma generator 106 into the semiconductor processing chamber 114 (for example, as shown by 105).

[0025] Referring to the exemplary embodiment shown in Figure 3, by providing a branching block 306, the output section of the plasma generator 106 is fluidically coupled to the semiconductor processing chamber 114 (arranged as shown in Figure 1), allowing light emitted from excited radicals to be transmitted to the viewport 104. In this case, the first end of the channel in the branching block 306 is coupled to the conduit 308 (the conduit 308 is coupled to the output section of the plasma generator 106), the second end of the channel in the branching block 306 is coupled to the viewport 104, and the third end of the channel in the branching block 306 is coupled to the semiconductor processing chamber 114 (for example, via one or more pipes, conduits, etc.). Therefore, the radicals (excited by the plasma generator 106) and diluent gas in the outflow generated by the RPS 110 can be transported to the semiconductor processing chamber 114 through the conduit 308 and the branching block 306, while the light transmitted to the viewport 104 can be transmitted to the spectrometer 102. In the embodiment shown in Figure 3, the same branching block 306 is used to transport radicals in the effluent generated by the RPS 110 to the semiconductor processing chamber 114 and transmit light emitted by the radicals (excited by the plasma generator 106) and diluent gas to the viewport 104. However, it will be understood that other devices may be used for a similar purpose. For example, the viewport 104 may be directly located at a suitable position on the plasma generator 106, and pipes or conduits may be coupled at different positions to the output section of the plasma generator 106 to which the effluent can be transmitted.

[0026] In the embodiment shown in Figure 2, the plasma generator 106 is located within the semiconductor processing chamber 114 (which can be provided as a chamber capable of performing one or more processes such as plasma-enhanced chemical vapor deposition (PECVD), plasma-enhanced atomic layer deposition (PEALD), and etching, or any combination thereof).

[0027] Referring to Figures 1 and 2, the viewport 104 provides a direct viewing path into the plasma generated by the plasma generator 106, thereby enabling the spectrometer to be optically coupled to the plasma generator 106. In the embodiment shown in Figure 1, the viewport 104 is located on the plasma generator 106, and the optical input of the spectrometer 102 is attached to the viewport 104. In the embodiment shown in Figure 2, the viewport 104 is located on the semiconductor processing chamber 114 (in a position where light from radicals excited by the plasma generator 106 can be viewed), and the optical input of the spectrometer 102 is attached to the viewport 104. However, in another embodiment, the spectrometer 102 may be located away from the viewport 104, and light can be transmitted from the viewport 104 to the spectrometer 102 using one or more optical fibers or other waveguides. Regardless of how the spectrometer 102 is optically coupled to the plasma generator 106, by providing a first optical element (e.g., a light-gathering element, not shown) in the viewport 104, the light can be focused, thereby increasing the amount of light generated from radicals excited by the plasma generator 106 and transmitting it to the spectrometer 102 as an optical signal. Furthermore, by providing a second optical element (e.g., a collimator, not shown), the light transmitted from the first optical element can be collimated so that the light entering the spectrometer 102 becomes a collimated optical signal.

[0028] Spectrometer 102 is operable to measure light emitted by radicals and diluent gases (when excited by plasma generator 106) and to generate measurement data based on the measured light. In some embodiments, spectrometer 102 is configured to measure optical signals within a continuous wavelength range, for example, 200 nm to 1100 nm, 650 nm to 840 nm, etc. In other embodiments, spectrometer 102 is configured to measure optical signals within one or more discrete wavelengths, or within a range of relatively narrow wavelengths. For example, spectrometer 102 may be provided as an OPTOFLASH spectrometer engine manufactured by NEWPORT. Exemplary embodiments of discrete-wavelength (or narrow-linewidth) spectrometers that can be used as spectrometer 102 are described in detail in U.S. Patent No. 8,633,440, which is incorporated herein by reference. In some cases, the use of discrete-wavelength (or narrow-linewidth) spectrometers may be advantageous over continuous-wavelength spectrometers due to their relatively low cost, small size, and high data acquisition / processing speed. An example embodiment of a discrete-wavelength spectrometer that can be used as spectrometer 102 will be described in more detail with reference to Figure 4.

[0029] Referring to Figure 4, the discrete wavelength spectrometer 400 (also referred to herein simply as "spectrometer 400") may comprise a beam splitter 402 (e.g., a dichroic beam splitter), a first band-pass filter 404a, a second band-pass filter 404b, a first photodiode 406a, a second photodiode 406b, a first amplifier 408a, a second amplifier 408b, and an oscilloscope 410. Figure 4 also shows the aforementioned focusing element (identified as 412), collimator (identified as 414), and optical fiber 416 that optically couples the focusing element 412 and the collimator 414. However, in another embodiment, the optical fiber 416 may be omitted, in which case the focusing element 412 and the collimator 414 are provided as a single component that performs both functions of the focusing element 412 and the collimator 414.

[0030] The beam splitter 402 is used to split the incident light signal propagating along the input beam path 401 into a first light signal (e.g., having one or more wavelengths within the transmission band of the beam splitter 402 and propagating along a first beam path 418a shown as a dotted line in Figure 4) and a second light (e.g., having one or more wavelengths within the reflection band of the beam splitter 402 and propagating along a second beam path 418b shown as a dotted line in Figure 4). The wavelengths within the transmission band of the beam splitter 402 may be higher or lower than the wavelengths within its reflection band. The transition wavelength between the transmission and reflection bands of the beam splitter 402 may be adjusted or otherwise selected based on the type(s) of radicals and diluent gases present in the outflow generated by the RPS110. For example, if the RPS110 generates an outflow containing fluorine (F) radicals in an argon (Ar) diluent gas, the transition wavelength may be, for example, 725 nm (or a value near that). Therefore, any light in the first optical signal transmitted along the first beam path 418a by the beam splitter 402 has one or more wavelengths greater than 725 nm (or a value near there), and any light in the second optical signal reflected along the second beam path 418b by the beam splitter 402 has one or more wavelengths less than 725 nm (or a value near there).

[0031] The first band-pass filter 404a is positioned within the first beam path 418a and configured to produce a first filtered optical signal by transmitting only a portion of the spectrum in the first optical signal propagating along the first optical path 418a. Similarly, the second band-pass filter 404b is positioned within the second beam path 418b and configured to produce a second filtered optical signal by transmitting only a portion of the spectrum in the second optical signal propagating along the second optical path 418b. Each of the first band-pass filter 404a and the second band-pass filter 404b may have a passband center wavelength that is tuned or otherwise selected based on the type(s) of radicals present in the outflow generated by the RPS110. For example, when RPS110 generates an outflow containing fluorine (F) radicals in an argon (Ar) dilution gas, the first band-pass filter 404a may have a first passband center wavelength in the range of 750 nm (or a value near there) to 751 nm (or a value near there), for example, 750.4 nm (or a value near there), and the second band-pass filter 404b may have a second passband center wavelength in the range of 703 nm (or a value near there) to 704 nm (or a value near there), for example, 703.7 nm (or a value near there). The first band-pass filter 404a and the second band-pass filter 404b may each have a bandwidth (FWHM) of 7 nm, 5 nm, 4 nm, 3 nm, 2 nm, 1 nm, etc., or any value among these.

[0032] The first photodiode 406a is positioned optically downstream of the first band-pass filter 404a in the first beam path 418a, and the second photodiode 406b is positioned optically downstream of the second band-pass filter 404b in the second beam path 418b. The first photodiode 406a is operable to generate a current in response to light in the first filtered optical signal that is incident on the first photodiode 406a. Similarly, the second photodiode 406b is operable to generate a current in response to light in the second filtered optical signal that is incident on the second photodiode 406b. Generally, the configurations of the first photodiode 406a and the second photodiode 406b are determined by the wavelength(s) of the light emitted by radicals in the outflow stream of the RPS 110 and excited by the plasma generator 106. If the excited radical emits light in the visible range of the electromagnetic spectrum (e.g., 400 nm to 1100 nm), the first photodiode 406a and the second photodiode 406b can each be provided as silicon photodiodes. It should be noted that other types of devices may be used to convert the light transmitted by the band-pass filter into an electrical signal. For example, a photomultiplier tube may be used instead of a photodiode.

[0033] The currents generated by the first photodiode 406a and the second photodiode 406b can generally be considered to be proportional to the intensity of light incident on the photodiodes. In many cases, the amount of light reaching the first photodiode 406a and the second photodiode 406b is relatively small, so an amplifier can be used to amplify the current output from the photodiodes and convert it into a voltage signal (i.e., representing the intensity of light incident on each photodiode), and this signal can be measured by the oscilloscope 410. Therefore, the first amplifier 408a is electrically connected to the output of the first photodiode 406a, and the second amplifier 408b is electrically connected to the output of the second photodiode 406b. Each of the first amplifier 408a and the second amplifier 408b can be provided as a transimpedance amplifier. The outputs of the first amplifier 408a and the second amplifier 408b are each connected to the electrical input of the oscilloscope 410.

[0034] The oscilloscope 410 is operable to measure the voltage signals output by the first amplifier 408a and the second amplifier 408b, and to generate and output measurement data representing the measured voltage signals. For example, the measurement data output by the oscilloscope 410 can represent the first voltage level of the first voltage signal output by the first amplifier 408a (corresponding to the intensity of light emitted by the diluent gas in the outflow when excited by the plasma generator 106) and the second voltage level of the second voltage signal output by the second amplifier 408b (corresponding to the intensity of light emitted by the radicals in the outflow when excited by the plasma generator 106).

[0035] Although not shown in Figure 4, the housing surrounds the optical components such as the beam splitter 402, the first band-pass filter 404a, the second band-pass filter 404b, the first photodiode 406a, and the second photodiode 406b, thereby preventing ambient light from interfering with the operation of the optical components of the spectrometer 400, at least substantially. The collimator 414 may be part of the spectrometer 400 (for example, located inside the housing), or it may be detachably coupled to the outside of the housing (for example, at a position in the housing that defines the optical input port of the spectrometer 400).

[0036] The spectrometer 400, configured as described above exemplarily, is configured to simultaneously measure two channels corresponding to two different wavelength bands (i.e., a first filtered optical signal in a first wavelength band corresponding to a first band-pass filter 404a, and a second filtered optical signal in a second wavelength band corresponding to a second band-pass filter 404b) and generate corresponding measurement data. It will be understood that other embodiments of the spectrometer 400 may be configured to generate measurement data corresponding to filtered optical signals in two or more wavelength bands. For example, the spectrometer 102 may be provided as described above in U.S. Patent No. 8,633,440, which is incorporated herein by reference. Thus, the spectrometer 400 may be configured to generate measurement data corresponding to the intensity of one or more radicals present in the outflow stream generated by the remote plasma generator 110.

[0037] Although the spectrometer 400 has been described above as using a beam splitter 402 provided as a reflective dichroic element, it will be understood that the beam splitter 402 may be provided as one or more mirrors, 50:50 beam splitters, reflective dichroic elements, etc., or any combination thereof, to split or manipulate the incident optical signal into separate optical signals that ultimately propagate to separate band-pass filters and / or photodiodes. Furthermore, although the spectrometer 400 has been described above as simultaneously producing filtered optical signals using band-pass filters 404a and 404b associated with the beam splitter 402, filtered optical signals can be produced using other devices, and measurement data can be generated from the optical signals. For example, a filter assembly (e.g., a filter wheel) in which multiple passband filters (each having a different passband center wavelength) are mounted on an electrically operated movable frame may be used to generate a series of filtered optical signals. In this case, the frame may be repeatedly operated to selectively position different filters attached to the frame within the input beam path 401, thereby generating a series of filtered optical signals, which are then propagated to the photodiode as described above.

[0038] Referring again to Figures 1 and 2, the system controller 112 is communicatively coupled to the spectrometer 102 and the plasma generator 106 to control their operation. For example, if the spectrometer 102 is provided with the filter assembly described above, the operation of the filter assembly (e.g., to control which filter is positioned in the beam path at any given time) can be controlled to measure the filtered optical signal associated with the corresponding radical. The system controller 112 can control one or more parameters associated with the operation of the plasma generator 106, such as the applied power level and the timing of operation.

[0039] Optionally, the system controller 112 may be communicatively coupled to the remote plasma source 110 to control its operation, thereby adjusting the concentration of radicals output by the remote plasma source 110. For example, the system controller 112 may be configured to generate one or more commands that, when sent to the RPS 110 (or its associated controller), are valid for controlling the operation of the RPS 110.

[0040] Furthermore, the system controller 112 can receive measurement data (e.g., carried as one or more signals output from the spectrometer 102) and process the measurement data to calculate the radical concentration in the effluent of the RPS 110, as will be described in more detail later. In one embodiment, the system controller 112 can generate one or more commands to be output to the RPS 110 to control the operation of the RPS 110, for example, based on the calculated radical concentration in the effluent generated by the RPS 110.

[0041] In general, the system controller 112 can be communicatively coupled to the plasma generator 106 and / or spectrometer 102 via one or more wired or wireless, serial or parallel communication links (e.g., USB, RS-232, Ethernet, Firewire, Wi-Fi, RFID, NFC, Bluetooth, Li-Fi, SERCOS, MARCO, EtherCAT, etc., or any combination thereof). The system controller 112 includes one or more processors capable of generating the aforementioned control signals when executing instructions. The processors may be programmable processors capable of executing instructions (e.g., one or more general-purpose computer processors, microprocessors, digital signal processors, or any other suitable form of circuitry, such as programmable logic devices (PLDs), field-programmable gate arrays (FPGAs), field-programmable object arrays (FPOAs), application-specific integrated circuits (ASICs) (including digital, analog, and analog / digital mixed circuitry), or any combination thereof). Instruction execution may be performed on a single processor, distributed across processors, performed in parallel via processors within a device or a network of devices, or any combination thereof.

[0042] In one embodiment, the system controller 112 includes a tangible medium such as computer memory accessible by the processor (e.g., via one or more wired or wireless communication links). As used herein, computer memory (or more simply, “memory”) includes magnetic media (e.g., magnetic tape, hard disk drive, etc.), optical discs, volatile or non-volatile semiconductor memory (e.g., RAM, ROM, NAND flash memory, NOR flash memory, SONOS memory, etc.), etc., and can be accessed locally, remotely (e.g., via a network), or a combination thereof. Generally, instructions can be stored as computer software (e.g., executable code, files, instructions, library files, etc.), which can be readily created by those skilled in the art from the descriptions provided herein and can be written in, for example, C, C++, Visual Basic, Java, Python, Tel, Perl, Scheme, Ruby, assembly language, hardware description language (e.g., VHDL, VERILOG, etc.). Computer software is generally stored in one or more data structures carried by computer memory.

[0043] As described above, the system controller 112 can be operated to process the measurement data output by the spectrometer 102 and calculate the concentration of radicals in the effluent of the RPS 110. In one embodiment, the system controller 112 can be operated to calculate the concentration of radical species in the effluent of the RPS 110 according to the following formula.

number

[0044] Considering the above, an exemplary procedure for measuring the radical concentration in the effluent generated by the RPS110 using the OES light intensity measurement system and method described herein can begin by flowing a diluent gas into the RPS110, setting the diluent gas flow rate and pressure, and waiting for the diluent gas flow and pressure to stabilize. Then, the RPS110 is operated to generate plasma, and waiting for the diluent plasma to stabilize. Next, a radical precursor (e.g., NF3 gas) can be allowed to flow into the RPS110, then the precursor gas flow rate can be set, and waiting for the precursor gas flow and pressure to stabilize. Next, the plasma generator 106 is operated to generate plasma downstream of the RPS110. The downstream plasma is stabilized, and at this point, the glow discharge of the plasma generator 106 collects the light emitted by the radicals and diluent gas in the effluent and propagates it to the spectrometer 102. The spectrometer 102 generates measurement data as described above and transmits the measurement data to the system controller 112, which calculates the radical concentration in the effluent.

[0045] The above description illustrates embodiments and examples of the present invention and should not be construed as a limitation of the invention. While a small number of specific embodiments and examples have been described with reference to the drawings, those skilled in the art will readily understand that many modifications to the disclosed embodiments and examples, and even other embodiments, are possible without substantially departing from the novel teachings and merits of the invention. Accordingly, all such modifications described herein are intended to fall within the scope of the invention as defined in the claims. For example, those skilled in the art will understand that it is possible to combine any sentence, paragraph, example, or subject matter of any sentence, paragraph, example, or embodiment with some or all of the subject matter of other sentences, paragraphs, examples, or embodiments, unless such combination is incompatible with each other. Accordingly, the scope of the invention should be determined by the appended claims, and anything equivalent to the claims is included within the scope of the invention.

Claims

1. A system for determining the concentration of radicals in a particle stream generated by plasma delivered into a semiconductor processing chamber, A plasma generator having an inlet configured to receive an outflow of a particle stream containing radicals and diluent gases, wherein the plasma source is operable to generate a glow discharge to excite the radicals and diluent gases in the received outflow. A spectrometer optically coupled to the internal glow discharge region of the plasma generator, the spectrometer being operable to output measurement data representing the intensity of light emitted by the radicals and the diluent gas, A controller that is communicatively coupled to the spectrometer and is operable to calculate the concentration of radicals in the outflow based on the measurement data, A system that includes these features.

2. The system according to claim 1, wherein the plasma generator is externally operable outside the semiconductor processing chamber.

3. The system according to claim 1, wherein the plasma generator is an in-situ plasma generator that can operate within the semiconductor processing chamber.

4. The system according to claim 1, wherein the spectrometer is a continuous-wavelength spectrometer.

5. The system according to claim 1, wherein the spectrometer is a discrete wavelength spectrometer.

6. The system according to claim 1, wherein the controller is operable to generate one or more commands effective for controlling the operation of the particle flow source.

7. The system according to claim 1, further comprising a light-shielding feature connected to the inlet of the plasma source, wherein the light-shielding feature is configured to transport the outflow but to prevent light emitted by the remote plasma source from reaching the plasma generator.

8. The system according to claim 7, wherein the light-shielding feature portion includes at least one selected from the group consisting of a bent portion, a baffle, and a screen.

9. The system according to claim 1, further comprising a viewport coupled to the plasma source, wherein the viewport is configured to transmit light emitted by the excited radicals and the diluent gas in the received outflow stream.

10. The system according to claim 1, further comprising a remote plasma source fluidly coupled to the inlet of the plasma generator, wherein the remote plasma source is operable to generate the outflow.

11. A particle flow delivery system used in conjunction with a semiconductor processing chamber, A remote plasma source capable of generating an outflow of particle streams containing radicals and diluent gases, A plasma generator having an inlet configured to receive the outflow and an outlet configured to be coupled to the semiconductor processing chamber, wherein the plasma source is operable to generate a glow discharge for exciting the radicals and diluent gas in the outflow and to transport the outflow to the semiconductor processing chamber, A light-shielding feature portion is disposed between the remote plasma source and the plasma generator, wherein the light-shielding feature portion transports the outflow but is configured to prevent light emitted from the remote plasma source from reaching the plasma generator, A spectrometer optically coupled to the internal glow discharge region of the plasma source, and capable of outputting measurement data representing the intensity of light emitted by the radicals and the diluent gas, A controller that is communicatively coupled to the spectrometer and is operable to calculate the concentration of radicals in the outflow based on the measurement data, A particle flow delivery system equipped with the following features.

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