Method and apparatus for pulsed gas delivery with concentration measurement

Abstract

To provide a pulse gas control system, a pulse gas supply system, and a method for controlling the pulse gas supply system for providing an accurate molar supply amount of process gas to a process chamber.SOLUTION: The system and method of the present invention provide a more accurate molar delivery of process gas for each pulse of pulsed gas delivery by measuring the concentration of the process gas and controlling the amount of gas mixture delivered in a pulse of gas flow based on the received concentration of the process gas. Control of the molar feed rate for each pulse can be achieved by adjusting the flow set point, the pulse duration, or both.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] Related Applications This application is a continuation-in-part of U.S. Patent Application No. 16 / 742,172, filed January 14, 2020, the teachings of which are incorporated herein by reference in their entirety. [Background technology]

[0002] background In many processes involving pulsed gas delivery, such as atomic layer deposition (ALD) and atomic layer etching (ALE) processes, a precursor or process gas is mixed with a carrier gas. Due to the manner in which the process gas is typically generated, for example, because the power output of the chemical reaction that produces the process gas changes over time, the concentration of the process gas can vary during the process. However, it is important to provide the correct molar supply of process gas to the process chamber. Summary of the Invention

[0003] overview However, existing pulsed gas delivery systems can only guarantee the total molar amount in each pulse, which includes both process gas and carrier gas, and therefore the molar amount of process gas in each pulse can vary. Thus, there is a continuing need for a relatively precise molar delivery amount of process gas in a pulsed gas mixture. [Means for solving the problem]

[0004] A method and apparatus for pulsed gas delivery with concentration measurement is disclosed. The method and apparatus provide a relatively precise molar delivery amount of process gas for each pulse of pulsed gas delivery by measuring the concentration of the process gas and controlling the amount of gas mixture delivered in pulses of gas flow based on the received concentration of the process gas. Control of the molar delivery amount for each pulse can be achieved by adjusting the flow set point, the pulse duration, or both.

[0005] The pulse gas control system includes a gas concentration measurement system configured to measure a concentration of a process gas in a gas mixture. The pulse gas delivery system is configured to sense and control a flow of the gas mixture. The system receives the concentration of the process gas in the gas mixture measured by the gas concentration measurement system and controls the amount of the gas mixture delivered in the gas flow pulses based on the received concentration of the process gas to control the molar amount of the process gas delivered to the process chamber in each pulse.

[0006] The pulse gas supply system may be configured to adjust a flow set point of the gas mixture in a pulse, and the adjustment may be based on the concentration of the received process gas. The pulse gas supply system may set an initial target flow set point of the gas mixture inversely proportional to the received concentration of the process gas. The initial target flow set point may be set proportional to the process gas moles supply / pulse set point divided by the product of the pulse duration period multiplied by the concentration of the received process gas. The pulse gas supply system may adjust the flow set point in the pulse duration period based on an altered measurement of the process gas concentration in the pulse duration period. The adjustment of the flow set point may be based on the relationship:

[0007]

number

[0008] The gas concentration measurement system can include an optical gas sensor, a surface acoustic wave device, an ultrasonic sensor, a mass spectrometer, or a thermal conductivity detector. The gas concentration measurement system can be disposed in series between a source of the gas mixture and a pulsed gas supply system to receive the gas mixture from the source and provide the gas mixture to the pulsed gas supply system. It can be disposed to receive a sample of the gas mixture from a sample line that samples the flow of the gas mixture from the source to the pulsed gas supply system. The process chamber to which the pulsed gas supply system is configured to supply process gas can be one of an atomic layer deposition (ALD) process, an atomic layer etching (ALE) process, a through-silicon-via (TSV) process, a pulsed deep reactive ion etching (DRIE) process, a plasma-enhanced chemical vapor deposition (CVD) process, and a plasma-enhanced etching process.

[0009] The pulsed gas delivery system can be configured to adjust a flow setpoint of the gas mixture in a pulse. The pulsed gas delivery system can be configured to adjust a pulse duration used to deliver the gas mixture to the process chamber and can be configured to adjust the pulse duration by terminating the pulse duration when the total molar amount of delivered process gas is equal to or greater than the process gas delivery / pulse setpoint. The pulsed gas delivery system can be configured to adjust both the flow setpoint of the gas mixture and the pulse duration in a pulse.

[0010] The pulsed gas supply system can be configured to receive the concentration of the process gas in the gas mixture at an update rate that is at least 10 times a pulse frequency corresponding to a pulse duration period of the pulsed gas supply system. The system can have a heater configured to maintain at least a portion of a flow of the gas mixture having the process gas at an elevated temperature. The pulsed gas supply system can be configured to control the heater to maintain a substantially constant elevated temperature of the process gas along at least a portion of the flow of the gas mixture between the source and the process chamber.

[0011] A method for controlling a pulsed gas delivery system includes measuring a concentration of a process gas in a gas mixture, receiving the concentration of the process gas in the gas mixture by the pulsed gas delivery system, and controlling the amount of the gas mixture being delivered in pulses of gas flow by the pulsed gas delivery system based on the received concentration of the process gas to control the molar amount of the process gas delivered to the process chamber in each pulse.

[0012] The method may include adjusting a flow set point of the gas mixture in the pulse. The flow set point of the gas mixture may be adjusted based on the concentration of the received process gas. An initial target flow set point of the gas mixture may be set to be inversely proportional to the concentration of the received process gas. The initial target flow set point may be set to be proportional to the process gas moles delivered / pulse set point divided by the product of the pulse duration period multiplied by the concentration of the received process gas. The method may include adjusting the flow set point in the pulse duration period based on a modified measurement of the process gas concentration in the pulse duration period. The method may include adjusting the flow set point based on the relationship:

number

[0013] Here, Q sp (t) is the flow set point, k is the conversion constant from moles to flow units, and M sp where Q(t) is the process gas moles delivered / pulse set point, Q(t) is the measured flow rate of the pulsed gas delivery system, C(t) is the received process gas concentration, Δt is the pulse duration period, t is the current time, and t is the initial point in time of the pulse duration period. The method can include adjusting the flow set point with time during the pulse duration period until the pulse duration period is completed. The method can include maintaining a constant pulse duration while adjusting the flow set point.

[0014] The method may include measuring the concentration of the process gas in the gas mixture using an optical gas sensor, a surface acoustic wave device, an ultrasonic sensor, a mass spectrometer, or a thermal conductivity detector. The pulsed gas supply system may be used to supply process gas to one of an atomic layer deposition (ALD) process, an atomic layer etching (ALE) process, a through-silicon via (TSV) process, a pulsed deep reactive ion etching (DRIE) process, a plasma-enhanced chemical vapor deposition (CVD) process, and a plasma-enhanced etching process. The method may include adjusting a flow setpoint of the gas mixture in a pulse. The method may include adjusting a pulse duration used to supply the gas mixture to the process chamber and adjusting the pulse duration by terminating the pulse duration when the total molar amount of process gas supplied is equal to or greater than the process gas moles supply / pulse setpoint. The method may include adjusting the flow setpoint of the gas mixture in a pulse and adjusting the pulse duration.

[0015] The method can include receiving a concentration of the process gas in the gas mixture at an update rate that is at least 10 times a pulse frequency corresponding to a pulse duration period of the pulsed gas delivery system. The method can include using a heater to maintain at least a portion of a flow of the gas mixture having the process gas at an elevated temperature and controlling the heater to maintain a substantially constant elevated temperature of the process gas along at least a portion of the flow of the gas mixture between the source and the process chamber. [Brief explanation of the drawings]

[0016] BRIEF DESCRIPTION OF THE DRAWINGS The foregoing subject matter is best understood from the following more particular description of illustrative embodiments that are illustrated in the accompanying drawings, in which like reference numerals refer to like parts throughout the different views. The drawings are not necessarily to scale, but instead are illustrative of the embodiments. The emphasis is on examples.

[0017] [Figure 1A] FIG. 1A is a schematic block diagram of a pulsed gas control system using concentration measurement in an in-line configuration in accordance with one embodiment of the present invention.

[0018] [Figure 1B] FIG. 1B is a schematic block diagram of a pulsed gas control system using concentration measurements in a sample line configuration in accordance with one embodiment of the present invention.

[0019] [Figure 2-3] 2 and 3 are part of a schematic block diagram of a process for controlling a pulsed gas delivery system by adjusting the flow set point of a gas mixture in a pulse according to one embodiment of the present invention.

[0020] [Figure 4] FIG. 4 is a schematic block diagram of a pulsed gas control system using an additional carrier gas line according to one embodiment of the present invention.

[0021] [Figure 5] FIG. 5 is a schematic block diagram of a host controller interacting with a pulsed gas delivery system according to one embodiment of the present invention.

[0022] [Figure 6] FIG. 6 is a simplified schematic block diagram of a controller that may be used as such a component, including, for example, as the pulse molar volume control processor of FIG.

[0023] [Figure 7-8]7 and 8 are portions of a schematic block diagram of a process for controlling a pulsed gas delivery system by adjusting the pulse duration used to deliver a gas mixture to a process chamber according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0024] Detailed Description An exemplary embodiment is described below.

[0025] In conventional gas delivery systems, precursor gases or other process gases are typically generated by a chemical or physical process continuing in the gas supply, such as by vaporizing a liquid or solid. For example, a carrier gas, such as nitrogen, can be flowed through an ampoule containing the precursor material to generate a vapor, which bubbles out of the ampoule and contains a mixture of the carrier gas and precursor gas. The ampoule is heated to a high temperature to vaporize the solid or liquid precursor; as a result, the rate of evaporation is often highly dependent on the pressure, temperature, and surface area involved in the reaction. The rate of the chemical or physical reaction used to generate the process gas can vary widely during the generation of the process gas.

[0026] Due to this varying rate of process gas production, conventional pulsed gas delivery systems may often deliver molar amounts of process gas that vary significantly between pulses, even when the total volume of the combined process gas and carrier gas is maintained relatively constant. However, such variations in process gas volume can produce large variations in the results of the manufacturing process in which the process gas is being used, for example, by producing varying thicknesses of deposited layers on surfaces in atomic layer deposition (ALD) processes.

[0027] To address these and other shortcomings of conventional systems, concentration measurements are used to provide accurate molar delivery of gas mixtures in pulsed gas delivery systems, as described further herein.

[0028] FIG. 1A is a schematic block diagram of a pulsed gas control system 100a using concentration measurement in an in-line configuration according to one embodiment of the present invention. A gas source 101a flows a gas mixture of a process gas with a carrier gas into the system, and the gas mixture flows through a gas concentration measurement system 104a and a pulsed gas delivery system 106a. In the embodiment of FIG. 1A, the gas concentration measurement system 104a and the pulsed gas delivery system 106a have an "in-line" or serial flow configuration. In this embodiment, the gas concentration measurement system 104a is disposed in series between the source 101a of the gas mixture and the pulsed gas delivery system 106a to receive the gas mixture from the source 101a and provide the gas mixture to the pulsed gas delivery system 106a. It should be understood that other flow configurations may also be used, such as in FIG. 1B. In FIG. 1A, the pulsed gas delivery system 106a senses and controls the flow of the gas mixture. The gas concentration measurement system 104a measures the concentration 108a of a process gas in the gas mixture. The pulsed gas supply system 106a receives the process gas concentration 108a measured by the gas concentration measurement system 104a and controls the amount of the gas mixture being supplied in the gas flow pulses based on the received process gas concentration 108a to control the molar amount 110a of the process gas supplied to the process chamber in each pulse.

[0029] FIG. 1B is a schematic block diagram of a pulsed gas control system using concentration measurement in a sample line configuration according to one embodiment of the present invention. In this example, gas concentration measurement system 104b is configured to receive a sample of the gas mixture from sample line 107b, which samples the gas flow of the gas mixture from source 101b to pulsed gas delivery system 106b. Gas source 101b flows the gas mixture into pulsed gas delivery system 106b, and gas concentration measurement system 104b receives the sample of the gas mixture from sample line 107b, which branches off from flow line 109b through which gas source 101b flows the gas mixture into pulsed gas delivery system 106b. Thus, gas concentration measurement system 104b can measure concentration 108b of the process gas in the gas mixture and provide it to pulsed gas delivery system 106b. The system is otherwise similar to that of FIG. 1A.

[0030] Using gas concentration measurement system 104a / 104b, the system of FIGS. 1A and 1B obtains the concentration 108a / 108b of precursor or other process gases in the gas mixture, and this information is fed into pulsed gas delivery system 106a / 106b. Pulsed gas mole delivery system 106a / 106b adjusts the total molar amount of the gas mixture—including both process gas and carrier gas—with each pulsed gas mole delivery so that the molar amount of the process gas remains constant. Adjusting the total molar amount of the gas mixture can be achieved by adjusting the flow setpoint, the pulse duration, or both. In some embodiments, the system can change only the flow setpoint without changing the pulse duration so that the pulsed gas delivery is synchronized with other instruments in the manufacturing process, such as radio frequency (RF) generation in the process chamber.

[0031] The pulsed gas supply systems 106a / 106b may be, for example, pulsed mass flow controllers (MFCs) or molar supply devices. For example, the pulsed gas supply systems 106a / 106b may be any of the pulsed gas supply systems taught in U.S. Patent No. 10,353,408 B2 to Ding et al., U.S. Patent No. 7,628,860 B2 to Shajii et al., U.S. Patent No. 7,615,120 B2 to Shajii et al., U.S. Patent No. 7,829,353 B2 to Shajii et al., and U.S. Patent Application Publication Nos. 2014 / 0190571 to Ding et al. and 2019 / 0243392 A1 to Ding et al., the teachings of each of which are incorporated by reference in their entirety.

[0032] The gas concentration measurement system 104a / 104b may be or include, for example, an optical gas sensor, a surface acoustic wave device, an ultrasonic sensor, a mass spectrometer, or a thermal conductivity detector. For example, a gas sensor based on infrared (IR) absorption, such as a tunable filter spectrometer (TFS), a non-dispersive infrared (NDIR) sensor, or a Fourier transform infrared spectrometer (FTIR) sensor, may be used. Gas sensors based on infrared absorption have good sensitivity and selectivity, their measurement is non-invasive, and they can be placed in-line with the supply system. However, other concentration measurement methods, such as other optical gas sensors, surface acoustic wave (SAW) sensors, ultrasonic sensors, mass spectrometry, and thermal conductivity detectors, may also be used.

[0033] The process chamber to which the pulsed gas supply system is configured to supply process gas 110a may be one of, for example, an atomic layer deposition (ALD) process, an atomic layer etching (ALE) process, a through silicon via (TSV) process, a pulsed deep reactive ion etching (DRIE) process, a plasma enhanced chemical vapor deposition (CVD) process, a plasma enhanced etching process, or any process requiring a pulsed gas mixture. The process may be, for example, part of a semiconductor manufacturing process, but may also be used in other processes. As used herein, a pulsed deep reactive ion etching (DRIE) process is, for example, a highly anisotropic etching process typically used to create deep, penetrating, steep-sided holes and trenches with high aspect ratios in wafers and other substrates. In one example, the DRIE process is a pulsed or time-multiplexed etching process such as any of those taught in U.S. Pat. No. 5,501,893 A to Laermer et al., U.S. Pat. No. 6,531,068 B2 to Laermer et al., and U.S. Pat. No. 6,284,148 B1 to Laermer et al., the teachings of each of which are incorporated by reference in their entirety.

[0034] 2 and 3 are schematic block diagrams of a process for controlling a pulsed gas delivery system by adjusting the flow set point of a gas mixture in a pulse according to one embodiment of the present invention. In the embodiment of FIGS. 2 and 3, the pulsed gas delivery system adjusts the flow set point of the gas mixture in a pulse to achieve a precise molar amount of process gas in each pulse. The pulsed gas delivery system can maintain a constant pulse duration while adjusting the flow set point. However, it should be understood that the pulsed gas delivery system can also adjust the pulse duration used to deliver the gas mixture to the process chamber, or can perform both adjustments of the flow set point and adjustment of the pulse duration of the gas mixture in a pulse (see, e.g., FIGS. 7 and 8).

[0035] In the process of FIG. 2, a host controller (which may be implemented, for example, as a host processor of a tool in which a pulsed gas delivery system is used, see 505 in FIG. 5) determines the precursor (or other process gas) molar set point (M sp ) and pulse duration period (Δt) to a pulsed gas delivery system, such as a pulsed mass flow controller (MFC) (see 106a / 106b in FIGS. 1A and 1B) (the mole set point and pulse duration may be present in the signal sent to or from the host controller 505 in FIG. 5). The mole set point may be, for example, at a level of about 100 micromoles / pulse, although it should be understood that other molar amounts may also be used. The pulsed gas delivery system may set 230 an initial target flow set point for the gas mixture to be inversely proportional to the concentration of the received process gas. For example, as shown in step 230 in FIG. 2, the pulsed gas delivery system may receive the process gas moles delivery / pulse set point (M sp) (e.g., based on a proportionality constant k) to set the initial target flow setpoint Q sp (t) can be set. The host controller (see 505 in FIG. 5) then sends a pulsed gas delivery trigger signal (which may be present in signals 515 sent to and from the host controller 505 in FIG. 5) to the pulsed gas delivery system 240 (see 106a / 106b in FIGS. 1A and 1B) to begin delivery at the beginning of the pulse duration period (t0). The process continues 242 as shown in FIG. 3.

[0036] 2 and 3, the pulsed gas supply system adjusts the flow set point of the gas mixture based on the concentration of the received process gas. Continuing from the process of FIG. 2 at 242 in FIG. 3, the pulsed gas supply system (see 106a / 106b in FIGS. 1A and 1B) adjusts its flow (e.g., by controlling internal control valve 513 in FIG. 5) to a target flow set point Q sp (t) 350. The pulsed gas supply system (see 106a / 106b in FIGS. 1A and 1B) adjusts the flow setpoint Q during the pulse duration based on the altered measurement of the process gas concentration during the pulse duration. sp3, the pulsed gas delivery system obtains updated precursor gas (or other process gas) concentration information C(t) from a gas concentration measurement device (see 104a / 104b in FIGS. 1A and 1B) during delivery. The concentration information C(t) can be updated in real time based on a clock period of the host processor (505 in FIG. 5) or the pulse molar quantity control processor (see 511 in FIG. 5), or both, which, in one example, may be approximately 5 milliseconds or another clock period. The update rate of the concentration information C(t) can be set by the method described in connection with FIG. 5 below. Then, for example, at 370 in FIG. 3, the pulsed gas delivery system (106a / 106b in FIGS. 1A and 1B) can adjust the flow setpoint based on the relationship:

[0037]

number

[0038] It should be understood that other techniques for setting the flow set point may be used other than those of Figures 2 and 3. For example, in another technique, C(t) in step 370 is calculated as a function of the measured flow rate Q, where C(t) may vary relatively rapidly over the pulse duration. m (t) based on the change in the flow set point Q sp While (t) is still varying, it could be treated as being constant over the pulse duration, based on the theory that it changes only a small amount over the duration of each pulse.

[0039] 7 and 8 are schematic block diagrams of a process for controlling a pulsed gas delivery system by adjusting the pulse duration in a pulse according to one embodiment of the present invention. While these figures show adjusting only the pulse duration, it should be understood that the method may also include adjusting both the pulse duration and the flow set point. In FIG. 7, the host controller (see 505 in FIG. 5) adjusts the precursor (or other process gas) molar set point (M sp7, the host controller (see 505 in FIG. 5) transmits 720 the initial process gas concentration information 108a / 108b, C(t), and the pulse duration period (Δt) to a pulsed gas delivery system (see 106a / 106b in FIG. 1A and FIG. 1B), such as a pulsed mass flow controller (MFC). The host controller (see 505 in FIG. 5) then transmits 730 a pulsed gas delivery trigger signal (which may be present in a signal 515 transmitted to and from the host controller 505 in FIG. 5) to the pulsed gas delivery system (see 106a / 106b in FIG. 1A and FIG. 1B) to begin delivery at an initial time (t) of the pulse duration period. The pulsed gas delivery system obtains initial process gas concentration information 108a / 108b, C(t), from the gas concentration measurement device 104a / 104b, as shown in step 740 in FIG. 7, and calculates the flow set point as follows:

number

[0040] Continuing from the process of FIG. 7 at 742 of FIG. 8, the pulsed gas delivery system (see 106a / 106b of FIGS. 1A and 1B) regulates its flow (e.g., by controlling the internal control valve 513 of FIG. 5) to a flow setpoint Q sp The pulsed gas delivery system (see 106a / 106b in FIGS. 1A and 1B) monitors the total molar amount of precursor gas delivered during delivery. For example, at 860 in FIG. 8, the pulsed gas delivery system obtains updated precursor gas (or other process gas) concentration information C(t) from a gas concentration measurement device (see 104a / 104b in FIGS. 1A and 1B) during delivery. Then, at 870 in FIG. 8, the pulsed gas delivery system (106a / 106b in FIGS. 1A and 1B) can update the total molar amount of precursor gas delivered during delivery as follows:

number

[0041] FIG. 4 is a schematic block diagram of a pulsed gas control system using an additional carrier gas line according to one embodiment of the present invention. In this embodiment, a pressure controller 402 is shown controlling the flow of carrier gas through a precursor (or other process gas) ampoule 403. A gas concentration measurement device 404 (e.g., sensor 404) provides concentration information 408 to a pulsed gas delivery system 406 (e.g., a pulsed mass flow controller), which then provides a precise molar amount of process gas to a process chamber 412 in each pulse. Here, the gas concentration measurement device 404 and pulsed gas delivery system 406 are integrated together as an atomic layer deposition (ALD) precursor delivery controller 414, although it should be understood that the system may be used for other processes as well. Additionally, in FIG. 4, an additional carrier gas line 416 may be used to mix the pulsed gas supply 410 with a desired amount of additional carrier gas from the carrier gas line 416, the flow of which may be controlled by its own carrier gas flow controller 418 (e.g., controlled by the host controller 505 in FIG. 5). It should be understood that the use of an additional carrier gas line 416 is not required and that other flow circuits may be added to the systems taught herein.

[0042] FIG. 5 is a schematic block diagram of a host controller 505 interacting with a pulsed gas delivery system 506 according to one embodiment of the present invention. In FIG. 5, a gas mixture flows from a gas source 501 to a pulsed gas delivery system 506 through a gas concentration measurement device 504. The gas concentration measurement device 504 measures the concentration of the process gas according to the techniques taught herein and provides a concentration signal 508 to a pulse molar quantity control processor 511 of the pulsed gas delivery system 506. The pulse molar quantity control processor 511 may include suitable components (such as a specially programmed application-specific integrated circuit or microprocessor) programmed to implement the techniques taught herein based on the concentration signal 508 provided by the gas concentration measurement device 504 and to communicate with and control the other components of the pulsed gas delivery system 506. The pulsed gas delivery system 506 also includes an internal control valve 513 to regulate flow. Upon completion of the pulse duration, the pulsed gas delivery system 506 provides 510 a precise molar amount of process gas in a pulse to a process chamber 512. The pulsed gas supply system 506 also has a flow sensor 507 that senses the flow and a flow set point Q sp Flow rate Q measured as close as possible to m and a flow rate control processor 509 that uses separate conventional techniques to control the flow rate of the pulsed gas. The flow sensor may be a thermal flow sensor, a differential pressure flow sensor, or other sensor used in conventional mass flow controllers. Additionally, the host controller 505 communicates with the pulsed molar quantity control processor 511 via signals 515 to coordinate the control techniques taught herein implemented by the pulsed molar quantity control processor 511 in conjunction with the host tool. For example, signals 515 may include a molar set point, a pulse duration, and a pulsed gas delivery trigger signal provided by the host controller 505 to the pulsed molar quantity control processor 511.

[0043] The gas concentration measurement device 504 can transmit a concentration signal 508, and the pulsed gas delivery system 506 can receive the concentration signal 508 at an update rate that is appropriately faster than the system's pulse duration period (Δt). This update rate can effectively set the update rate of feedback loops within the system, such as the loops in steps 350, 360, 370, and 380 of FIG. 3. A fast update rate can help ensure, for example, that concentrations are sensed at a rate that is fast enough for the transition rates of temperature and process gas changes within the system. In one example, it has been found useful to transmit the concentration signal 508 and update the feedback loops at an update rate that is at least 10 times greater than the system's pulse frequency. For example, a 200 millisecond pulse duration period has a 5 Hz frequency, and in this case, the update rate of the concentration signal 508 and feedback loop (steps 350, 360, 370, and 380 of FIG. 3) should have a frequency of at least 50 Hz, i.e., at least 10 times faster than the pulse duration frequency. The update rate of the concentration signal 508 and feedback loop can be set in a variety of different possible ways. For example, the update rate can be set by the rate of update of the gas concentration measurement device 504, or it can be controlled by the host controller 505, or it can be controlled by the pulse molar quantity control processor 511 (or a separate processor in communication therewith) at a fixed rate or at a rate adjusted based on the pulse duration period provided by the host controller 505. In one example, the pulse molar quantity control processor 511 sets the update rate as a multiple of 10 times the pulse frequency determined based on the pulse duration period (Δt) provided by the host controller 505 and communicates this update rate to the gas concentration measurement device 504. Alternatively, the gas concentration measurement device 504 can be preselected to have an update rate 504 large enough to exceed a criteria, such as 10 times the maximum expected pulse frequency.

[0044] The pulsed gas delivery system 506 may further include a heater 519 configured to maintain at least a portion of the process gas flow at an elevated temperature. As discussed above, precursor gases or other process gases are typically generated by a chemical or physical process ongoing in the gas delivery, such as by vaporizing a liquid or solid. Therefore, it may be advantageous to utilize a heater 519 to maintain some or all of the process gas flow at a temperature that maintains the process gas in its gaseous state so that the process gas does not revert to a solid or liquid state by cooling as the gas flows through the system. The heater 519 may heat one or more components through which the process gas flows, such as the gas source 501, the gas concentration measurement device 504, the flow sensor 507, and the internal valve 513, as well as the gas flow lines between these components and that carry the gas to the process chamber. In one example, the system uses the heater 519 to heat the gas concentration measurement device 504, the flow sensor 507, and the internal valve 513. For example, the temperature can be maintained above 150°C, such as above 200°C, such as about 230°C. The heater 519 can be used to avoid cold spots along the gas flow path and can be used, for example, to maintain a substantially constant elevated temperature along the gas flow path or along at least a portion of the gas flow path between the gas source 501 and the process chamber 512. By "substantially constant," it is intended that the elevated temperature can be maintained, for example, within ±20°C of the temperature to be maintained, such as within ±10°C or within ±5°C of the temperature to be maintained. The heater 519 can be an active or passive heating element and can be mounted in a thermally conductive relationship between one or more of the components it heats, such as the gas source 501, the gas concentration measurement device 504, the flow sensor 507, and the internal valve 513, and between these components and the gas flow lines flowing gas to the process chamber 512 or above all of these components.The heater 519 can be internal, external, or both internal and external to the pulsed gas delivery system 506. Additionally, the temperature of the heater 519 can be controlled by a heater control processor 517, which can be controlled by (or be part of) the pulse molar quantity control processor 511. For example, the heater control processor can receive temperature information from a temperature sensor 521 positioned in a heat-sensing arrangement with the heater 519, or with one of the components it heats, or with other components of the system. Based on the temperature information, the heater control processor 517 can provide a signal to the heater 519 to adjust the degree or location of heating provided to one or more components.

[0045] The various techniques described herein are implemented using a controller and may include computer-implemented components such as a pulse molar quantity control processor 511, a flow rate control processor 509, and a heater control processor 517 (see FIG. 5). FIG. 6 is a simplified schematic block diagram of a controller that may be used for such components, including, for example, as the pulse molar quantity control processor 511 of FIG. 5. The control techniques described herein can be implemented using, for example, hardware such as a controller 691 including one or more processors 692 that may include one or more application-specific integrated circuits (ASICs) 693, 694, application software running on the one or more processors 692 of the controller 691, and sensor and / or actuator lines 695-699 that provide electronic signals to and from systems described herein (such as the gas concentration measurement device 504, host controller 505, flow rate control processor 509, flow sensor 507, internal valve 513, heater control processor 517, heater 519, and temperature sensor 521 of FIG. 5), where signals can provide electronic signals between activated components in the systems described herein (such as actuator lines that provide electronic signals to activated valves or other controlled components). Controller 691 may also include a user input module 681, which may include components (such as a keyboard, touchpad, and associated electronic circuitry in conjunction with processor 692 and memory 682) for receiving user input such as set points. Controller 691 may also include memory 682 for storing information and for implementing procedures under the control of computer hardware and software. It should be understood that other control hardware, including at least partially pneumatic control hardware, may also be used.

[0046] Portions of the methods and systems described above can be implemented using one or more computer systems, for example, to allow pulsed gas delivery with concentration measurement. For example, the techniques can be implemented using hardware, software, or a combination thereof. When implemented in software, the software code can be executed on any suitable processor or collection of processors, whether provided within a single computer or distributed among multiple computers. For example, the pulse molar quantity controller processor 511, the flow rate control processor 509, and the heater controller processor 517 can be provided within a single component or distributed among multiple components.

[0047] Advantages of embodiments may include, for example, the ability to provide precise molar amounts of precursor or other process gases in each gas pulse. The methods and apparatus can be applied to a variety of different processes, including atomic layer deposition (ALD) and atomic layer etching (ALE) processes, with precursor or other process gases in the mixture. Furthermore, the methods and apparatus can be applied when the concentration of the precursor or process gas is varying in the process, including a wide range of precursor variations. Control can be fast, without the need to control the chemical or physical aspects of the gas mixing or reaction. The methods and apparatus are integrated and simplify process monitoring and control.

[0048] As used herein, the terms "gas" or "gases" include the terms "vapor" or "vapors" when these terms are considered to be different.

[0049] As used herein, a "process gas" can be or include a precursor gas, and can be or include any of a variety of other possible gases used in processes, including any pulsed gas mixtures, regardless of whether they are precursor gases. For example, in one embodiment, a pulsed WF gas mixture can be used. The process in which the process gas is used can be, for example, an atomic layer deposition (ALD) process, an atomic layer etching (ALE) process, a through-silicon via (TSV) process, a pulsed deep reactive ion etching (DRIE) process, a plasma-enhanced chemical vapor deposition (CVD) process, a plasma-enhanced etching process, or any process requiring a pulsed gas mixture. The process can be, for example, part of a semiconductor manufacturing process, but can also be used in other processes.

[0050] The teachings of all patents, published patent applications, and references cited herein are hereby incorporated by reference in their entirety.

[0051] While example embodiments have been particularly shown and described herein, those skilled in the art will understand that various changes in form and detail may be made therein without departing from the scope of the embodiments as encompassed by the appended claims.

Claims

1. 1. A pulse gas control system comprising: a gas concentration measurement system configured to measure a concentration of a process gas in the gas mixture; a pulsed gas delivery system configured to sense and control the flow of the gas mixture, receive the concentration of the process gas in the gas mixture measured by the gas concentration measurement system, and control the amount of the gas mixture delivered in pulses of gas flow based on the received concentration of the process gas to control the molar amount of the process gas delivered to the process chamber in each pulse; A system having:

2. 10. The pulsed gas control system of claim 1, wherein the pulsed gas supply system is configured to adjust a flow set point of the gas mixture in the pulse.

3. 3. The pulsed gas control system of claim 2, wherein the pulsed gas supply system is configured to adjust the flow set point of the gas mixture based on the received concentration of the process gas.

4. 4. The system of claim 3, wherein the pulsed gas delivery system sets an initial target flow set point for the gas mixture inversely proportional to the received concentration of the process gas.

5. 5. The system of claim 4, wherein the pulse gas supply system sets the initial target flow set point to be proportional to the process gas moles supply / pulse set point divided by the product of the pulse duration period multiplied by the received concentration of the process gas.

6. The pulsed gas supply system adjusts the process gas concentration during the pulse duration. adjusting the flow set point during the pulse duration based on the altered measurement of the flow rate; 3. The system of claim 2, wherein

7. The pulsed gas delivery system adjusts the flow set point based on the relationship: [Equation 1] Here, Q sp (t) is the flow set point, k is the conversion constant from moles to flow units, M sp is the process gas moles delivery / pulse set point, and Q m where (t) is the measured flow rate of the pulsed gas delivery system, C(t) is the received process gas concentration, Δt is the pulse duration period, t is the current time, and t 0 7. The system of claim 6, wherein: is an initial point in the pulse duration period.

8. 7. The system of claim 6, wherein the pulsed gas delivery system adjusts the flow set point with time during the pulse duration period until the pulse duration period is completed.

9. 3. The system of claim 2, wherein the pulsed gas delivery system maintains a constant pulse duration while adjusting the flow set point.

10. The gas concentration measurement system includes an optical gas sensor, a surface acoustic wave device, an ultrasonic sensor, a mass spectrometry device, and a The system of claim 1 comprising a spectrometer or a thermal conductivity detector.

11. 10. The system of claim 1, wherein the gas concentration measurement system is disposed in series between a source of the gas mixture and the pulsed gas delivery system to receive the gas mixture from the source and to provide the gas mixture to the pulsed gas delivery system.

12. 10. The system of claim 1, wherein the gas concentration measurement system is positioned to receive a sample of the gas mixture from a sample line that samples a gas flow of the gas mixture from a source to the pulsed gas delivery system.

13. 10. The system of claim 1, wherein the process chamber to which the pulsed gas delivery system is configured to deliver the process gas is one of an atomic layer deposition (ALD) process, an atomic layer etching (ALE) process, a through silicon via (TSV) process, a pulsed deep reactive ion etching (DRIE) process, a plasma enhanced chemical vapor deposition (CVD) process, and a plasma enhanced etching process.

14. 10. The system of claim 1, wherein the pulsed gas delivery system is configured to adjust a pulse duration used to deliver the gas mixture to the process chamber.

15. 15. The system of claim 14, wherein the pulsed gas supply system is configured to adjust the pulse duration by terminating the pulse duration when the total molar amount of process gas supplied is equal to or greater than a process gas moles supply / pulse set point.

16. 15. The system of claim 14, wherein the pulsed gas delivery system is configured to adjust a flow set point of the gas mixture in the pulse and to adjust the pulse duration.

17. 10. The system of claim 1, wherein the pulsed gas supply system is configured to receive the concentration of the process gas in the gas mixture at an update rate that is at least 10 times a pulse frequency corresponding to a pulse duration period of the pulsed gas supply system.

18. 10. The system of claim 1, further comprising a heater configured to maintain at least a portion of the flow of the gas mixture with the process gas at an elevated temperature.

19. 20. The system of claim 18, wherein the pulsed gas supply system is configured to control the heater to maintain a substantially constant elevated temperature of the process gas along at least a portion of the flow of the gas mixture between a source and the process chamber.

20. 1. A method for controlling a pulsed gas delivery system, comprising: measuring a concentration of a process gas in the gas mixture; receiving the concentration of the process gas in the gas mixture by the pulsed gas delivery system; controlling the amount of gas mixture provided in pulses of gas flow by the pulsed gas delivery system based on the received concentration of the process gas to control the molar amount of the process gas delivered to the process chamber in each pulse; A method having the following.

21. 21. The method of claim 20, further comprising adjusting a flow set point of the gas mixture in the pulse.

22. the flow setting of the gas mixture based on the received concentration of the process gas.

22. The method of claim 21, further comprising adjusting the points.

23. 23. The method of claim 22, further comprising setting an initial target flow set point for the gas mixture inversely proportional to the received concentration of the process gas.

24. 24. The method of claim 23, further comprising setting the initial target flow set point proportional to the process gas moles supply / pulse set point divided by the product of the pulse duration period multiplied by the received concentration of the process gas.

25. 22. The method of claim 21, further comprising adjusting the flow setpoint during a pulse duration based on the altered measurement of the process gas concentration during the pulse duration.

26. adjusting the flow set point based on the relationship: [Equation 2] Here, Q sp (t) is the flow set point, k is the conversion constant from moles to flow units, M sp is the process gas moles delivery / pulse set point, and Q m where (t) is the measured flow rate of the pulsed gas delivery system, C(t) is the received process gas concentration, Δt is the pulse duration period, t is the current time, and t 0 26. The method of claim 25, wherein: is an initial point in the pulse duration period.

27. 26. The method of claim 25, further comprising adjusting the flow set point with time during the pulse duration period until the pulse duration period is completed.

28. 22. The method of claim 21, comprising maintaining a constant pulse duration while adjusting the flow set point.

29. 21. The method of claim 20, comprising measuring the concentration of the process gas in the gas mixture using an optical gas sensor, a surface acoustic wave device, an ultrasonic sensor, a mass spectrometer, or a thermal conductivity detector.

30. 21. The method of claim 20, comprising using the pulsed gas delivery system to supply the process gas to one of an atomic layer deposition (ALD) process, an atomic layer etching (ALE) process, a through silicon via (TSV) process, a pulsed deep reactive ion etching (DRIE) process, a plasma enhanced chemical vapor deposition (CVD) process, and a plasma enhanced etching process.

31. 21. The method of claim 20, further comprising adjusting a pulse duration used to deliver the gas mixture to the process chamber.

32. 32. The method of claim 31, comprising adjusting the pulse duration by terminating the pulse duration when the total molar amount of process gas delivered is equal to or greater than a process gas moles delivered / pulse set point.

33. 32. The method of claim 31, comprising adjusting a flow set point of the gas mixture in the pulse and adjusting the pulse duration.

34. 21. The method of claim 20, comprising receiving the concentration of the process gas in the gas mixture at an update rate that is at least 10 times a pulse frequency corresponding to a pulse duration period of the pulsed gas delivery system.

35. 21. The method of claim 20, including using a heater to maintain at least a portion of the flow of the gas mixture with the process gas at an elevated temperature.

36. 36. The method of claim 35, further comprising controlling the heater to maintain a substantially constant elevated temperature of the process gas along at least a portion of the flow of the gas mixture between a source and the process chamber.

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