Method and apparatus for calibrating a concentration sensor for precursor delivery - Patents.com

Abstract

To provide methods and apparatus for controlling precursor flow.SOLUTION: In embodiments, methods and apparatuses for controlling precursor flow to a deposition chamber, include: an ampoule to output a precursor; a sensor assembly communicatively coupled to the ampoule; and a control system, wherein the control system is configured to calibrate the sensor assembly during flow of a precursor or a chemical standard through the sensor assembly.SELECTED DRAWING: Figure 1A

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE Embodiments of the present disclosure generally relate to methods and apparatus for calibrating concentration sensors for precursor delivery in semiconductor deposition systems and controlling precursors in chemical deposition processes. More particularly, methods and apparatus are provided for on-tool calibration verification and recalibration of concentration sensors for precursor delivery to semiconductor deposition chambers. [Background technology]

[0002] Semiconductor device fabrication involves chemical deposition processes for forming thin layers with precise thickness control, including on three-dimensional structures. Such chemical deposition processes include chemical vapor deposition (CVD) and atomic layer deposition (ALD), among other processes.

[0003] Such chemical deposition processes can include supplying precursors from a solid source, such as an ampoule, a gas source, or a liquid source. For example, precursors can be supplied from an ampoule to a process chamber, where the precursors can react to form a layer or sub-layer on a substrate. The inventors have observed that, inter alia, due to the deposition of precursors in the sensor, over time, the concentration sensor can become inaccurate and drift, thereby causing drift in the raw or calibrated concentration sensor readings, so that the amount of precursor supplied is not properly characterized. An inaccurate or uncalibrated concentration sensor, or a delay in detecting or compensating for the sensor drift, can problematically cause variability in the supply of precursors between substrates, which in turn leads to variability in the uniformity and reproducibility of the deposited film.

[0004] The inventors have also observed that problematic variations can occur between two or more sensor assemblies in different devices. To maintain robust and uniform deposition in two or more deposition systems, consistent calibration is required between the multiple systems.

[0005] Therefore, the inventors have provided an improved embodiment for calibrating a concentration sensor assembly for precursor delivery and controlling precursors in a chemical deposition process. Summary of the Invention

[0006] Methods and apparatus are provided herein for controlling precursor flow to a deposition chamber. In some embodiments, a method for controlling precursor flow to a deposition chamber includes flowing a precursor or a chemical standard through a sensor assembly and a gas delivery system configured to flow the precursor into the deposition chamber, and calibrating the sensor assembly based on the flow rate of the precursor or the chemical standard through the sensor assembly.

[0007] In some embodiments, an apparatus for controlling a precursor flow rate to a deposition chamber includes an ampoule for outputting a precursor, a sensor assembly communicatively coupled to the ampoule, and a control system configured to calibrate the sensor assembly during flow of a precursor or a chemical standard through the sensor assembly.

[0008] In some embodiments, a non-transitory computer-readable storage medium is provided having instructions stored thereon that, when executed by a processor, cause the method to perform a method including flowing a precursor or a chemical standard through a sensor assembly and a gas delivery system configured to flow the precursor into a deposition chamber, and calibrating the sensor assembly based on a flow rate of the precursor or the chemical standard through the sensor assembly.

[0009] Other and further embodiments of the present disclosure are described below.

[0010] Embodiments of the present disclosure, briefly summarized above and discussed in more detail below, can be understood by reference to the exemplary embodiments of the present disclosure as illustrated in the accompanying drawings, which, however, depict only typical embodiments of the present disclosure and therefore should not be considered as limiting the scope, since the present disclosure may admit of other equally effective embodiments. [Brief description of the drawings]

[0011] [Figure 1A] FIG. 1 illustrates a system for chemical deposition according to an embodiment of the present disclosure. [Figure 1B] FIG. 1B illustrates one embodiment of a control system for the system of FIG. 1A. [Figure 1C] FIG. 1 illustrates another system for chemical deposition according to an embodiment of the present disclosure. [Figure 1D] FIG. 1 illustrates another system for chemical deposition according to an embodiment of the present disclosure. [Figure 1E] FIG. 1 illustrates another system for chemical deposition according to an embodiment of the present disclosure. [Figure 2A] 1A-1C illustrate the operation of a sensor assembly according to an embodiment of the present disclosure. [Figure 2B] 1A-1C illustrate the operation of a sensor assembly according to an embodiment of the present disclosure. [Diagram 3] FIG. 1 provides an exemplary process flow according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] For ease of understanding, the same reference numbers have been used, where possible, to designate identical elements common to the figures. The figures are not drawn to scale and may be simplified for clarity. Elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.

[0013] In embodiments, the present disclosure relates to a method and apparatus for controlling precursor flow rate to a deposition chamber, the apparatus including an ampoule for outputting precursor, a sensor assembly communicatively coupled to the ampoule, and a control system configured to calibrate the sensor assembly during or with the flow of precursor or chemical standard through the sensor assembly. In embodiments, the method and apparatus are configured to measure the initial accuracy and drift in accuracy over time of the concentration sensor, thereby isolating the drift in sensor accuracy from the actual drift in the chemical precursor delivery of the semiconductor processing tool. In embodiments, periodic recalibration of the concentration sensor device prevents the drift in sensor accuracy. Furthermore, in some embodiments, a method is provided for compensating for the drift in accuracy of the concentration sensor, thereby enabling precise control of the chemical precursor delivery during semiconductor processing and / or extending the life of the concentration sensor between preventive maintenance cycles. In embodiments, the present disclosure includes a method and apparatus configured to use and measure the concentration sensor accuracy against a chemical standard.

[0014] The embodiments described herein provide novel processing and control of precursors in chemical deposition processes, such as atomic layer deposition (ALD) processes. ALD generally involves sequential exposure to two or more reactants to deposit a given monolayer of material. In embodiments, chemical deposition processes can be performed to deposit any suitable material, including oxides, nitrides, carbides, dielectrics, semiconductors, or metals. The chemical deposition process can include control of precursor flow rates.

[0015] Referring now to FIG. 1A, a system 100 for chemical deposition according to the present disclosure is shown. In an embodiment, the system 100 is configured for chemical deposition. In an embodiment, the system 100 is configured to use at least one precursor that is typically delivered as a gaseous species to a process chamber, referred to as a deposition chamber 110. In an embodiment, the system 100 can be utilized to perform chemical vapor deposition (CVD) or atomic layer deposition (ALD). The embodiment is not limited in this context. The system 100 includes a source, such as an ampoule 104, which can include a solid, liquid, or gas. The ampoule 104 can be maintained at an elevated temperature to generate a gaseous species, which may be referred to herein as a precursor. The ampoule 104 can be coupled to a delivery system 114 configured to direct at least one gaseous species, and in some cases multiple gaseous species, to the deposition chamber 110, as in known CVD or ALD systems. For example, the delivery system 114 can include multiple gas lines, such as a first gas line 70 and a second gas line 71, valves, such as a first valve 80, a second valve 81, a third valve 82, and a flow controller, such as a flow controller 85. At least a portion of the delivery system 114 can be housed within the high temperature chamber 106, which is maintained in a precisely controlled isothermal environment to ensure that precursors remaining in the high temperature chamber 106 have the same temperature.

[0016] In an embodiment, the system 100 is an apparatus for controlling a precursor flow rate to a deposition chamber, the apparatus including an ampoule 104 for outputting a precursor, a sensor assembly 108 communicatively coupled to the ampoule 104, and a control system, the control system 112 configured to calibrate the sensor assembly 108 during flow of the precursor or chemical standard through the sensor assembly. In some embodiments, the sensor assembly 108 is disposed downstream of the ampoule 104 containing the precursor. In some embodiments, the sensor assembly 108, one or more supply lines, such as the first gas line 70 and the second gas line 71, valves, such as the first valve 80, the second valve 81, the third valve 82, and a flow controller, such as the flow controller 85, are within the high temperature chamber 106. In some embodiments, the system 100 is an apparatus configured to flow a precursor of known concentration into an enclosed volume of a supply system, the enclosed volume including or consisting of an ampoule 104 containing a precursor fluidly coupled to the sensor assembly 108, the enclosed volume being isothermal. In an embodiment, the enclosed volume of the delivery system is an interior volume created by closing the first valve 80 and closing the third valve 82. In an embodiment, the enclosed volume of the delivery system includes the second valve 81 in an open position such that the precursor material in gas form can flow through the second valve 81. In an embodiment, the enclosed volume may further include one or more additional chambers, such as reservoirs containing carrier gas chemistry.

[0017] In an embodiment, system 100 may further include a sensor assembly 108 configured to monitor the flow rate of at least one precursor between ampoule 104 and deposition chamber 110. Sensor assembly 108 may be coupled to a control system 112, which may output information or signals to a user, as well as send control signals to control operating parameters of system 100, including temperature, precursor flow rates, etc. Details of one embodiment of control system 112 are shown in FIG. 1B and discussed further below.

[0018] In an embodiment, the control system 112 may be implemented with a combination of hardware and software. The control system 112 may include various hardware elements, software elements, or a combination of hardware / software. Examples of hardware elements may include devices, logic devices, components, processors, microprocessors, circuits, processor circuits, circuit elements (e.g., transistors, resistors, capacitors, inductors, etc.), integrated circuits, application specific integrated circuits (ASICs), and programmable logic devices (PLDs). Examples of hardware elements may further include digital signal processors (DSPs), field programmable gate arrays (FPGAs), memory units, logic gates, registers, semiconductor devices, chips, microchips, chipsets, and the like. Examples of software elements may include software components, programs, applications, computer programs, application programs, system programs, software development programs, machine programs, operating system software, middleware, firmware, software modules, routines, subroutines, and functions. Examples of software elements may further include methods, procedures, software interfaces, application program interfaces (APIs), instruction sets, computing code, computer code, code segments, computer code segments, words, values, symbols, or any combination thereof. The decision whether an embodiment is implemented using hardware and / or software elements may depend on any number of factors, such as desired computation rates, power levels, thermal tolerances, processing cycle budgets, input data rates, output data rates, memory resources, data bus speeds, and other design or performance constraints, as desired for a given implementation.

[0019] As an example, control system 112 can include various hardware outputs, which may be embodied as signals for controlling other components of system 100, output at a user interface, or otherwise. In some examples, the hardware outputs may be utilized as inputs by control system 112 to control components of system 100, as described in more detail below. In one embodiment, the hardware outputs include temperature, such as the temperature of ampoule 104, and may also output gas pressure, precursor concentration, and health monitors (reference signals).

[0020] In an embodiment, the outputs can be collected periodically, intermittently, and synchronously or separately from each other (in time). In an embodiment, the functions can be performed by the control system 112. Non-limiting examples of the functions include chamber flux (μmol / sec) to model the precursor flux delivered to the wafer, integrated chamber flux (μmol) for the sum of the precursor flux across the wafer, integrated flux of the ampoule, end of life detection to signal the need for ampoule replacement, defect detection to detect and classify defects, and concentration detection to correct errors in concentration readings, such as when comparing concentration readings to known precursor concentrations or known chemical standard concentrations.

[0021] 1B, in an embodiment, the control system 112 may include a processor 150, such as a known type of microprocessor, a dedicated semiconductor processor chip, a general purpose semiconductor processor chip, or a similar device. The control system 112 may further include a memory or memory unit 160 coupled to the processor 150, the memory unit 160 including a flux control routine 162. As described in more detail below, the flux control routine 162 may function in the processor 150 to control precursor fluxes or precursor flow rates of the system 100. In some embodiments, the flux control routine 162 may include one or more of an end of life processor 164, an excursion processor 166, a clog detection processor 168, a temperature control processor 170, and a concentration calibration processor 172.

[0022] In an embodiment, the memory unit 160 includes an article of manufacture. In one embodiment, the memory unit 160 can include a non-transitory computer-readable or machine-readable medium, such as optical, magnetic, or semiconductor storage. The storage medium can store various types of computer-executable instructions to implement one or more of the logic flows described herein. Examples of computer-readable or machine-readable storage media can include tangible media capable of storing electronic data, including volatile or non-volatile memory, removable or non-removable memory, erasable or non-erasable memory, writeable or re-writeable memory, and the like. Examples of computer-executable instructions can include any suitable type of code, such as source code, compiled code, interpreted code, executable code, static code, dynamic code, object-oriented code, visual code, and the like. The embodiments are not limited in this context.

[0023] In some embodiments, the present disclosure includes a non-transitory computer-readable storage medium having stored thereon instructions that, when executed by a processor, cause the execution of a method, the method including flowing a precursor or a chemical standard through a sensor assembly and a gas delivery system configured to flow the precursor into a deposition chamber, and calibrating the sensor assembly based on a flow rate of the precursor or the chemical standard through the sensor assembly.

[0024] In some embodiments, the memory unit 160 can include a system database 180 that includes parameters for operating the system 100. Exemplary parameters include, for example, a baseline concentration sensor assembly value of a preselected chemical standard or a preselected precursor, a baseline ampoule side temperature, and a baseline ampoule bottom temperature, which can be set as a starting point for control operations to be performed. Other parameters that are subject to control can include flow rates as well as deposition times. Additional parameters can be used to assign limits to ensure that the temperature of the process remains within a safe range, which can also be stored in the system database 180. Among these parameters are ampoule side temperature minimum, ampoule side temperature maximum, ampoule bottom temperature minimum, ampoule bottom temperature maximum, hot chamber temperature, and precursor degradation temperature.

[0025] In an embodiment, the sensor assembly 108 may be configured with suitable components for monitoring the precursors, including electromagnetic radiation, acoustic signals, and the like. The embodiments are not limited in this context. The sensor assembly 108 may determine the precursor flux or concentration by measuring the change in signal strength of an appropriate signal transmitted through the sensor assembly 108. In an embodiment, the concentration may include, for example, the percentage of the precursor in the total gas. Non-limiting examples of concentrations that may be detected with the sensor assembly 108 include 0.01 to 10,000 parts per million (ppm) of the precursor in the gas. With reference to FIGS. 2A and 2B, the sensor assembly 108 may include a light source 120, such as an infrared, visible, or ultraviolet light source, and a detector 122 facing the light source 120. The detector 122 may be a detector compatible with the type of radiation source used for the light source 120. The sensor assembly 108 may further include a chamber, shown as a cell 124, configured to receive and direct the precursor 126 as it travels from the ampoule 104 to the deposition chamber 110. As in FIG. 2A, when the precursor 126 is not present in the cell 124, the detector 122 may record a signal, such as a background signal. The background signal may represent the transmitted (detected) intensity as a function of the wavelength of the radiation from the light source 120. In some embodiments, the background signal may be featureless. When the precursor 126 is present in the cell 124, the precursor may absorb the radiation emitted by the light source 120, and the detector 122 records the precursor signal. In embodiments, the precursor signal may exhibit peaks, although the precursor signal may include multiple features, including multiple peaks in some embodiments. In embodiments, the presence of the precursor in the cell 124 may reduce the overall intensity of the detected radiation in the precursor signal, as opposed to the background signal. In embodiments, the recording of the background signal, as well as monitoring the precursor signal over multiple instances, is utilized to control the operation of the deposition process.

[0026] In an embodiment such as that shown in FIG. 1A, the sensor assembly 108 may be calibrated or recalibrated by determining the concentration of the chemical precursor in the cell 124 (FIG. 2B) under static conditions by creating an enclosed volume that includes both the open chemical precursor ampoule 104 and the sensor assembly 108, such as a concentration sensor assembly with a cell 124. The temperature of the enclosed volume is precisely controlled and measured, and in an embodiment is isothermal. In an embodiment, the concentration of the chemical precursor in the sensor assembly 108 with the cell 124 is determined from the known vapor pressure of the chemical precursor at the temperature of the enclosed volume. In an embodiment, the light absorption by the precursor 126 may be directly proportional to the partial pressure of the precursor 126 in the cell 124. Thus, physical modeling may be utilized to calculate the precursor flux in numerous instances based on repeated measurements of the precursor signal while accounting for drift in sensor accuracy, thereby facilitating better control of the chemical deposition process involving the precursor 126 by reducing or eliminating actual drift in the chemical precursor delivery. In addition to measuring the precursor flux, the cell pressure, such as the total pressure of the cell 124, may also be measured.

[0027] Referring back to FIG. 1A , the chemical precursor of known concentration can flow into the delivery system 114 through the flow controller 85, the first gas line 70, the first valve 80, the ampoule 104, the second gas line 71, the second valve 81, the sensor assembly 108, the third valve 82, and optionally one or more additional chambers, such as a reservoir containing carrier gas chemistry. In an embodiment, the first valve 80 and the third valve 82 are closed to create a sealed volume between the first valve 80 and the third valve 82 that includes the open ampoule 104 and the sensor assembly 108, such as a concentration sensor assembly. In an embodiment, the sealed volume includes the chemical precursor of known concentration under static conditions. In an embodiment, the sealed volume between the first valve 80 and the third valve 82 is contained within the high temperature chamber 106, which is maintained in a precisely controlled isothermal environment to ensure that the precursors within the high temperature chamber 106 have the same temperature. In an embodiment, the concentration of the chemical precursor in the sensor cell can then be estimated from the known vapor pressure of the chemical precursor at the temperature of the sealed volume. Based on the determined concentration of the chemical precursor, the sensor assembly 108 can be calibrated, recalibrated, or have an on-tool calibration verification. In an embodiment, calibrating the sensor assembly 108 compensates for, among other things, sensor drift due to deposition of precursors in the sensor assembly 108 over the life of the sensor assembly 108. Calibrating the sensor assembly 108 on-tool facilitates better control of the chemical deposition process involving the precursor 126.

[0028] Referring now to FIG. 1C, another system for chemical deposition according to an embodiment of the present disclosure is shown. In an embodiment, the system 100 is configured for chemical deposition according to an embodiment of the present disclosure. In an embodiment, the system 100 is configured to use at least one precursor that is typically delivered as a gaseous species to a process chamber, such as a deposition chamber 110. In an embodiment, the system 100 can be utilized to perform chemical vapor deposition (CVD) or atomic layer deposition (ALD). In an embodiment, the system 100 includes a source, such as an ampoule 104, which can include a solid, liquid, or gas. The ampoule 104 can be maintained at an elevated temperature to generate a gaseous species, which may be referred to herein as a precursor. The ampoule 104 can be coupled to a delivery system configured to direct at least one gaseous species, and in some cases multiple gaseous species, to the deposition chamber 110, as in known CVD or ALD systems. For example, the delivery system may include multiple gas lines, such as a first gas line 70 and a second gas line 71, valves, such as a first valve 80, a second valve 81, a third valve 82, a fourth valve 83, and a flow controller, such as a flow controller 85. In an embodiment, the system 100 includes a sensor assembly 108 as described above. The sensor assembly 108 may be coupled to a control system 112, which may output information or signals to a user as well as send control signals to control the operating parameters of the system 100, including temperature, precursor flow rate, and the like. Details of one embodiment of the control system 112 are described above. In an embodiment, a first pressure sensor 51 is located in the first gas line 70 between the flow controller 85 and the first valve 80. In an embodiment, a second pressure sensor 52 is located in the second gas line 71 downstream of the sensor assembly 108 and upstream of the deposition chamber 110. In an embodiment, a fourth valve 83 is disposed between the first valve 80 and the second valve 81, and the supply system is configured to bypass the ampoule 104 when desired via a bypass path formed between the first valve 80 and the second valve 81 by opening the fourth valve 84.In an embodiment, the fourth valve can be closed to configure a supply line, thereby forming a through ampoule path between the first valve 80 and the second valve 81 .

[0029] In embodiments, a known concentration of a chemical precursor under flow conditions may be provided to the sensor assembly 108 by measuring the steady state pressure change across the ampoule 104 when flowing through the ampoule 104 versus bypassing the ampoule 104. Other embodiments may include measuring the change in the rate of pressure rise in a process chamber or fixed volume to determine the change in flow rate. In some embodiments, the flow rate of the precursor from the ampoule 104 is determined. In embodiments, one or more pressure sensors, such as the first pressure sensor 51 or the second pressure sensor 52, and a flow controller 85 are included to measure the pressure change. In embodiments, the precursor concentration may be estimated by flowing multiple (three or more) different steady state flows through the supply line with the ampoule 104 bypassed, measuring the average pressure downstream of the ampoule 104 during the steady state flows, for example by measuring the pressure with the second pressure sensor 52, generating a functional mapping of the measured flow rate or change in flow rate between the bypass path and the through ampoule path, and modeling to estimate the additional flow rate from the precursor in the ampoule 104. In an embodiment, the total flow rate is the carrier flow rate plus the precursor flow rate. In an embodiment, the concentration is calculated as a percentage of the precursor flow rate of the total flow rate. Based on the determined concentration of the chemical precursor, the sensor assembly 108 can be calibrated, recalibrated, or have an on-tool calibration verification. In an embodiment, calibrating the sensor assembly 108 compensates for sensor drift due to deposition of precursors in the sensor assembly 108 over the life of the sensor assembly 108. Calibrating the sensor assembly 108 on-tool facilitates better control of the chemical deposition process including the precursor 126.

[0030] In an embodiment, the system 100 includes an apparatus for controlling precursor flow rate to a deposition chamber, the apparatus including an ampoule 104 for outputting a precursor, a sensor assembly 108 communicatively coupled to the ampoule 104, and a control system 112 configured to calibrate the sensor assembly 108 during flow of the precursor or chemical standard through the sensor assembly. In an embodiment, the sensor assembly 108 is disposed downstream of the ampoule 104 containing the precursor. In an embodiment, the first pressure sensor 51 is upstream of the sensor assembly 108 and the second pressure sensor 52 is downstream of the sensor assembly 108. In some embodiments, the system 100 further includes a supply system 114, such as a gas supply system, including one or more supply lines for a precursor path including a bypass path (between the first valve 80 and the second valve 81) upstream of the sensor assembly 108.

[0031] Referring now to FIG. 1D, another system for chemical deposition according to an embodiment of the present disclosure is shown. In an embodiment, the system 100 is configured to use at least one precursor, which is generally supplied as a gaseous species to a process chamber, referred to as a deposition chamber 110. In an embodiment, the system 100 can be utilized to perform chemical vapor deposition (CVD) or atomic layer deposition (ALD). In an embodiment, the system 100 includes a source, such as an ampoule 104, which can include a solid, liquid, or gas. The ampoule 104 can be maintained at an elevated temperature to generate a gaseous species, which may be referred to herein as a precursor. The ampoule 104 can be coupled to a supply system 114 configured to direct at least one gaseous species, and in some cases multiple gaseous species, to the deposition chamber 110, as in known CVD or ALD systems. For example, the supply system 114 can include multiple gas lines, such as a first gas line 70, a second gas line 71, a third gas line 72, valves, such as a first valve 80, a second valve 81, a third valve 82, and flow controllers, such as a flow controller 85 and a second flow controller 86, in communication with the third gas line 72 upstream of the sensor assembly 108. In an embodiment, the system 100 includes a sensor assembly 108 as described above. The sensor assembly 108 can be coupled to a control system 112, which can output information or signals to a user as well as send control signals to control the operating parameters of the system 100, including temperature, precursor flow rate, and the like. Details of one embodiment of the control system 112 are described above. In an embodiment, a calibration gas, including a chemical standard, can enter the third gas line 72 at arrow 93. In an embodiment, a carrier gas can enter the first gas line 70 at arrow 92.

[0032] In an embodiment such as that disclosed in FIG. 1D, a calibration gas of known concentration including chemical standards under flow conditions can enter the sensor assembly 108 via the supply line 77, and a sensor reading will be obtained based on the chemical standards. In an embodiment, the calibration gas including chemical standards is used in place of the target chemical precursor gas. In an embodiment, suitable calibration gases for use according to the present disclosure include chemical standards, such as precursor gas species that are chemically similar to the target chemical precursor by having a similar absorption spectrum and / or similar partial pressure dependence. In an embodiment, the chemical standard is preselected, for example, a chemical species or component that has an absorption spectrum similar to the target precursor. In an embodiment, the target precursor is the desired precursor for deposition. In an embodiment, the calibration gas and the chemical standards therein are gaseous under expected process conditions and are introduced through a second flow controller 86, such as a mass flow controller, so that known and appropriately controlled concentrations of the calibration gas and the chemical standards are introduced to the sensor assembly 108.

[0033] In the embodiment of FIG. 1D, the sensor assembly 108 can be calibrated using a calibration gas upon installation in the precursor delivery system. The calibration gas contains chemical standards that are spectrally similar to the precursors, so that the calibration gas can be used to correct small errors in the sensor assembly 108 or to calibrate raw sensor readings against a calibration gas of known concentration. In an embodiment, correcting the calibration of the sensor assembly 108 will depend on the sensor type and the original sensor calibration method, which includes testing the sensor assembly 108 at a range of concentration, temperature, and pressure conditions, and creating a functional mapping between the known calibration gas concentrations and the sensor assembly 108 readings. In an embodiment, the sensor concentration reading is equal to f(calibration gas concentration, pressure, temperature). In some embodiments, a calibration gas of known concentration containing chemical standards will be periodically introduced to the sensor assembly 108, and the drift of the readings from the expected readings or initial baseline readings will be measured. In an embodiment, the change in the measured concentration from the sensor calibration concentration of the original sensor assembly 108 may be from drift in the readings due to aging of optical components, deposition of chemicals in the optical path within the sensor assembly 108, or some other error.

[0034] In an embodiment, an apparatus for controlling precursor flow rate to a deposition chamber includes an ampoule 104 for outputting a precursor, a sensor assembly 108 communicatively coupled to the ampoule 104, and a control system 112, where the control system 112 is configured to calibrate the sensor assembly during flow of the precursor or chemical standard through the sensor assembly. In an embodiment, the sensor assembly 108 is disposed downstream of the ampoule 104 containing the precursor. In an embodiment, the sensor assembly 108 is disposed downstream of a supply line 77 that includes a second flow controller 86, such as a mass flow controller, and the chemical standard is supplied with a calibration gas in the supply line at arrow 93. In some embodiments, the system 100 is an apparatus configured to flow a chemical standard of known concentration into the sensor assembly and measure the chemical standard with the sensor assembly. In an embodiment, the chemical standard is preselected.

[0035] Referring now to FIG. 1E, another system for chemical deposition according to an embodiment of the present disclosure is shown. In an embodiment, the system 100 is configured to use at least one precursor, which is generally supplied as a gaseous species to a process chamber, referred to as a deposition chamber 110. In an embodiment, the system 100 can be utilized to perform chemical vapor deposition (CVD) or atomic layer deposition (ALD). In an embodiment, the system 100 includes a source, such as an ampoule 104, which can include a solid, liquid, or gas. The ampoule 104 can be maintained at an elevated temperature to generate a gaseous species, which may be referred to herein as a precursor. The ampoule 104 can be coupled to a supply system 114 configured to direct at least one gaseous species, and in some cases multiple gaseous species, to the deposition chamber 110, as in known CVD or ALD systems. For example, the delivery system can include multiple gas lines, such as a first gas line 70, a second gas line 71, valves, such as a first valve 80, a second valve 81, a third valve 82, and a flow controller, such as a flow controller 85, in communication with the first gas line 70 upstream of the ampoule 104. In an embodiment, the system 100 includes a sensor assembly 108 as described above. The sensor assembly 108 can be coupled to a control system 112, which can output information or signals to a user as well as send control signals to control the operating parameters of the system 100, including temperature, precursor flow rate, and the like. Details of one embodiment of the control system 112 are described above. In an embodiment, the carrier gas can enter the first gas line 70 at arrow 92. In an embodiment, a trap 113 is placed downstream of the sensor assembly 108.

[0036] The embodiment of FIG. 1E can be configured to measure the total flow rate of chemical precursors through the sensor assembly 108 by introducing an unknown concentration of precursors under flow conditions to the sensor assembly 108, followed by collecting all chemical precursors in a trap 113 downstream of the sensor assembly 108 and measuring the total mass. In an embodiment, the method includes maintaining a constant carrier gas flow over an extended period of time and measuring an average concentration sensor signal from the sensor assembly 108. The expected total precursor flow rate can be determined from the total carrier flow rate through the sensor assembly 108 and the average concentration sensor assembly reading and verified against the total mass of chemical precursors collected in the trap 113. The total precursor flow rate can also be determined from the total change in ampoule mass.

[0037] Referring now to FIG. 3, a process flow according to an embodiment of the present disclosure is shown as process sequence 300 for a method of controlling a precursor flow rate to a deposition chamber. In process sequence 302, the method includes flowing a precursor or a chemical standard through a sensor assembly and a gas delivery system configured to flow the precursor into the deposition chamber. In process sequence 304, the method includes calibrating the sensor assembly based on the flow rate of the precursor or the chemical standard through the sensor assembly. In some embodiments, the method includes the sensor assembly being positioned downstream of an ampoule containing the precursor. In some embodiments, the method includes the sensor assembly being positioned downstream of a supply line containing a mass flow controller and a chemical standard. In some embodiments, the method includes the sensor assembly being positioned upstream of a trap. In some embodiments, the method includes the sensor assembly and one or more supply lines being in a high temperature chamber. In some embodiments, the method includes a first pressure sensor being placed upstream of the sensor assembly and a second pressure sensor being downstream of the sensor assembly. In some embodiments, the method includes flowing a precursor of known concentration into a sealed volume of a delivery system, the sealed volume including an ampoule containing the precursor fluidly coupled to a sensor assembly, the sealed volume being isothermal. In some embodiments, the method includes flowing a chemical standard of known concentration into the sensor assembly and measuring the chemical standard with the sensor assembly. In some embodiments, the method includes preselecting the chemical standard.

[0038] In some embodiments, the disclosure relates to an apparatus including a processor and a memory unit coupled to the processor, the memory unit including a concentration control routine, the concentration control routine operative in the processor to monitor precursor concentrations, the concentration control routine including a concentration drift calculation processor for determining a precursor concentration drift value based on precursors or chemical standards flowing into a sensor assembly of a gas delivery system configured to deliver precursors to a deposition chamber. In some embodiments, the concentration drift calculation processor determines the precursor concentration value by flowing a known concentration precursor into an enclosed volume of the delivery system, the enclosed volume including an ampoule containing the precursor fluidly coupled to the sensor assembly, the enclosed volume being isothermal. In some embodiments, the precursor concentration value is determined from a known vapor pressure of the chemical standard at the temperature of the enclosed volume. In some embodiments, the concentration drift calculation processor determines the precursor concentration value as a percentage of the precursor flow rate of the total flow rate. In some embodiments, the concentration drift calculation processor determines the precursor concentration value as a percentage of the precursor flow rate of the total flow rate by flowing a plurality of steady state flows through the bypass valve, measuring the average pressure downstream of the ampoule, generating a mapping of the measured flow rates or changes in flow rates between the bypass path and the ampoule path, and determining the flow rate from the precursor in the ampoule. In some embodiments, the concentration drift calculation processor determines the precursor concentration value by flowing a chemical standard of known concentration through the sensor assembly and measuring the chemical standard with the sensor assembly. In embodiments, the chemical standard is preselected. In some embodiments, the concentration drift calculation processor determines the precursor concentration value by measuring the total mass of precursor that passed through the gas delivery system.

[0039] While the forgoing is directed to embodiments of the present disclosure, other and further embodiments of the present disclosure may be devised without departing from the basic scope thereof.

Claims

1. 1. A method for controlling an amount of a precursor flowing into a deposition chamber from an apparatus for controlling precursor flow rate, comprising: A. forming a sealed volume having a known volume between an inlet and an outlet of an apparatus for controlling a flow rate of the precursor, the sealed volume including an ampoule containing the precursor and a flow-through cell of a sensor assembly, the sealed volume being controlled to be isothermal at a known temperature sufficient to generate a portion of the precursor in a gaseous state within the sealed volume; B. measuring a signal from the sensor assembly and performing a calibration of an apparatus for controlling the precursor flow rate based on the measured signal from the sensor assembly, the known vapor pressure of the precursor at the known temperature, and the known volume; C. measuring the signal from the sensor assembly while flowing carrier gas into the deposition chamber through the inlet, the ampoule, the flow-through cell and the outlet at an effective carrier gas flow rate, and determining an amount of the precursor flowing into the deposition chamber based on the effective carrier gas flow rate, the signal from the sensor assembly and the calibration of an apparatus for controlling the precursor flow rate, wherein the sensor assembly includes an infrared, visible or ultraviolet light source and a corresponding detector; A method comprising:

2. A method for controlling an amount of a precursor flowing into a deposition chamber from an apparatus for controlling precursor flow, comprising: A. A known amount of a chemical standard is controlled to flow through a flow-through cell of a sensor assembly between an inlet and an outlet of the device for controlling the precursor flow rate; B. performing a calibration of an apparatus for controlling the precursor flow rate based on a signal from the sensor assembly that correlates to the amount of the chemical standard present in the flow-through cell; C. measuring the signal from the sensor assembly while flowing carrier gas into the deposition chamber through the inlet, the ampoule containing the precursor, the flow-through cell, and the outlet at an effective carrier gas flow rate, and determining an amount of the precursor flowing into the deposition chamber based on the effective carrier gas flow rate, the signal from the sensor assembly, and the calibration of an apparatus for controlling the precursor flow rate, wherein the sensor assembly includes an infrared, visible, or ultraviolet light source and a corresponding detector; A method comprising:

3. 1. A method for controlling an amount of a precursor flowing into a deposition chamber from an apparatus for controlling precursor flow rate, comprising: A. An ampoule containing the precursor and a flow-through cell of a sensor assembly are disposed upstream of a trap between an inlet and an outlet of a device for controlling the precursor flow rate; B. performing a calibration of an apparatus for controlling the precursor flow rate based on collecting the precursor in the trap and measuring the total mass of the precursor present in the trap; C. measuring a signal from the sensor assembly while flowing a carrier gas at an effective carrier gas flow rate into the deposition chamber through the inlet, the ampoule, the flow-through cell, and the outlet, and determining an amount of the precursor flowing into the deposition chamber based on the effective carrier gas flow rate, the signal from the sensor assembly, and the calibration of an apparatus for controlling the precursor flow rate; A method comprising:

4. A method for controlling an amount of precursor flowing into a deposition chamber from an apparatus for controlling precursor flow, comprising the steps of: A. The device for controlling the precursor flow rate is configured such that a carrier gas flows between the inlet and the outlet from the inlet through a flow-through cell of a sensor assembly and the outlet, bypassing an ampoule containing the precursor; B. Flowing the carrier gas through the inlet, the flow-through cell, and the outlet, bypassing the ampoule, and measuring a signal from the sensor assembly in the absence of the precursor to obtain a background signal from the sensor assembly, and performing a calibration of an apparatus for controlling the precursor flow rate based on the background signal from the sensor assembly; C. measuring the signal from the sensor assembly while flowing the carrier gas into the deposition chamber through the inlet, the ampoule, the flow-through cell and the outlet at an effective carrier gas flow rate, and determining an amount of the precursor flowing into the deposition chamber based on the effective carrier gas flow rate, the signal from the sensor assembly and the calibration of an apparatus for controlling the precursor flow rate, wherein the sensor assembly includes an infrared, visible or ultraviolet light source and a corresponding detector; A method comprising:

5. the apparatus for controlling the precursor flow rate further comprising a first pressure sensor disposed between the inlet and the ampoule and a second pressure sensor disposed downstream from the flow-through cell of the sensor assembly; flowing the carrier gas through the inlet, the flow-through cell, and the outlet, bypassing the ampoule, measuring a first pressure using the first pressure sensor while bypassing the ampoule, and measuring a second pressure using the second pressure sensor under a plurality of different carrier gas flow rates, and determining a background pressure difference between the first pressure and the second pressure for each of the plurality of different carrier gas flow rates; measuring the first pressure and the second pressure while flowing the carrier gas through the inlet, the device for controlling the precursor flow rate, the ampoule, the flow-through cell, and the outlet into the deposition chamber at an effective carrier gas flow rate, and determining an effective pressure differential at the effective carrier gas flow rate, wherein the calibration of the device for controlling the precursor flow rate is further based on each of the background pressure differentials; 5. The method of claim 4, wherein the determination of the amount of the precursor flowing into the deposition chamber is based on the effective carrier gas flow rate and the effective pressure differential.

6. The method of claim 2 , wherein the chemical standard is selected based on a chemical species or moiety having an absorption spectrum similar to that of the precursor.

7. 1. An apparatus for controlling precursor flow rate to a deposition chamber, comprising: an ampoule for outputting the precursor; a sensor assembly communicatively coupled to the ampoule; a control system configured to calibrate the sensor assembly during passage of the precursor through the sensor assembly; and wherein the control system comprises: A. forming a sealed volume having a known volume between an inlet and an outlet of an apparatus for controlling a flow rate of the precursor, the sealed volume including the ampoule containing the precursor and a flow-through cell of the sensor assembly, the sealed volume being controlled to be isothermal at a known temperature sufficient to produce a portion of the precursor in a gaseous state within the sealed volume; B. measuring a signal from the sensor assembly and performing a calibration of an apparatus for controlling the precursor flow rate based on the measured signal from the sensor assembly, the known vapor pressure of the precursor at the known temperature, and the known volume; C. measuring the signal from the sensor assembly while flowing carrier gas into the deposition chamber through the inlet, the ampoule, the flow-through cell and the outlet at an effective carrier gas flow rate, and determining an amount of the precursor flowing into the deposition chamber based on the effective carrier gas flow rate, the signal from the sensor assembly and the calibration of an apparatus for controlling the precursor flow rate, wherein the sensor assembly includes an infrared, visible or ultraviolet light source and a corresponding detector; An apparatus configured to control the apparatus to perform the steps of:

8. An apparatus for controlling precursor flow to a deposition chamber, comprising: an ampoule for outputting the precursor; a sensor assembly communicatively coupled to the ampoule; a control system configured to calibrate the sensor assembly during flow of a chemical standard through the sensor assembly; and wherein the control system comprises: A. A known amount of a chemical standard is controlled to flow through a flow-through cell of the sensor assembly between an inlet and an outlet of the device for controlling the precursor flow rate; B. performing a calibration of an apparatus for controlling the precursor flow rate based on a signal from the sensor assembly that correlates to the amount of the chemical standard present in the flow-through cell; C. measuring the signal from the sensor assembly while flowing carrier gas into the deposition chamber through the inlet, the ampoule, the flow-through cell and the outlet at an effective carrier gas flow rate, and determining an amount of the precursor flowing into the deposition chamber based on the effective carrier gas flow rate, the signal from the sensor assembly and the calibration of an apparatus for controlling the precursor flow rate, wherein the sensor assembly includes an infrared, visible or ultraviolet light source and a corresponding detector; An apparatus configured to control the apparatus to perform the steps of:

9. An apparatus for controlling precursor flow to a deposition chamber, comprising: an inlet and an outlet of a device for controlling the precursor flow rate; an ampoule for outputting the precursor; a sensor assembly communicatively coupled to the ampoule and positioned upstream of the trap; a control system configured to calibrate the sensor assembly during passage of the precursor through the sensor assembly; and Including, The control system comprises: performing a calibration of an apparatus for controlling the precursor flow rate based on collecting the precursor in the trap and measuring the total mass of the precursor present in the trap; measuring a signal from the sensor assembly while flowing a carrier gas at an effective carrier gas flow rate into the deposition chamber through the inlet, the ampoule, the sensor assembly, and the outlet, and determining an amount of the precursor flowing into the deposition chamber based on the effective carrier gas flow rate, the signal from the sensor assembly, and the calibration of an apparatus for controlling the precursor flow rate; An apparatus configured to control the apparatus to perform the steps of:

10. An apparatus for controlling a precursor flow rate to a deposition chamber, comprising: an inlet and an outlet of a device for controlling the precursor flow rate; an ampoule for outputting the precursor; a sensor assembly communicatively coupled to the ampoule; a control system configured to calibrate the sensor assembly; and Including, a first pressure sensor disposed between the inlet and the ampoule, and a second pressure sensor disposed downstream from a flow-through cell of the sensor assembly; the control system flowing a carrier gas through the inlet, the flow-through cell, and the outlet, bypassing the ampoule, measuring a first pressure using the first pressure sensor while bypassing the ampoule under a plurality of different carrier gas flow rates, and measuring a second pressure using the second pressure sensor, and determining a background pressure difference between the first pressure and the second pressure for each of the plurality of different carrier gas flow rates; measuring the first pressure and the second pressure while flowing the carrier gas through the inlet, the device for controlling the precursor flow rate, the ampoule, the flow-through cell, and the outlet into the deposition chamber at an effective carrier gas flow rate, and determining an effective pressure differential at the effective carrier gas flow rate, wherein the calibration of the device for controlling the precursor flow rate is further based on each of the background pressure differentials; wherein the determination of the amount of the precursor flowing into the deposition chamber is based on the effective carrier gas flow rate and the effective pressure differential. Device.

11. The apparatus of claim 8 , wherein the chemical standards are preselected.

12. 2. The method of claim 1, wherein the device for controlling the precursor flow rate is periodically calibrated according to A. and B. to compensate for drift in sensor accuracy.

13. 5. The method of claim 4, wherein the background signal from the sensor assembly is periodically measured and utilized to recalibrate an apparatus for controlling the precursor flow rate to compensate for drift in sensor accuracy.

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