WO2023069210A1

WO2023069210A1 - Exhaust monitoring apparatus and method for substrate processing systems

Info

Publication number: WO2023069210A1
Application number: PCT/US2022/043853
Authority: WO
Inventors: Shambhu Nath Roy; Yogananda TANGUTURI; Chetan Kumar Kammaragatte VAGEESHAPPA; Christopher C. GRIFFIN; Gautam Bhattacharyya; Sunil Kapoor
Original assignee: Lam Research Corporation
Priority date: 2021-10-22
Filing date: 2022-09-16
Publication date: 2023-04-27
Also published as: TW202334625A

Abstract

A gas exhaust monitoring apparatus includes a peripheral support frame and one or more collector elements. The one or more collector elements extend laterally across the peripheral support frame. The one or more collector elements include a plurality of openings configured to intake gas. A circuit board is coupled with the peripheral support frame. The circuit board includes a plurality of pressure sensors coupled to the one or more collector elements and a transmitter circuitry to transmit pressure readings from the plurality of pressure sensors. The pressure readings are utilized for computation of flow velocity of the gas.

Description

EXHAUST MONITORING APPARATUS AND METHOD FOR SUBSTRATE PROCESSING SYSTEMS

CLAIM OF PRIORITY

[0001] Tliis Application claims the benefit of priority to U.S. Provisional Patent Application No. 63/270,965, filed on October 22, 2021, and titled “EXHAUST MONITORING APPARATUS AND METHOD FOR SUBSTRATE PROCESSING SYSTEMS,” which is incorporated by reference in its entirety for all purposes.

BACKGROUND

[0002] Substrate processing systems arc used to perform treatments such as deposition and etching of film on substrates such as semiconductor wafers. For example, deposition may be performed to deposit conductive film, dielectric film, or other types of film using chemical vapor deposition (CVD), plasma enhanced CVD (PECVD), atomic layer deposition (ALD), plasma enhanced ALD (PEALD), and/or other deposition processes. During deposition, the substrate is arranged on a substrate support (c.g., a pedestal) and one or more precursor gases may be supplied to a processing chamber using a gas distribution device (e.g., a showerhead) during one or more process steps. The gases would then leave the processing chamber via one or more exhaust channels or tubes.

[0003] Gas pressure in a gas exhaust tube can be monitored by sensors that are coupled with one or more openings in the tube. Conventional sensors arc located external to the tube and attached to the one or more openings in the tube. Attachments may be made by one or more sensing tubes that can have substantially great lengths. Information conveyed by the sensing tubes are limited to gas pressure. Lack of localized measurements can lead to overcompensation of flow requirements and redesign of gas exhaust tubes among others. Overcompensation can be costly and can impose limitations on design. As such, it is desirable to have an inline gas flow monitor for obtaining localized measurements and for identify additional gas flow parameters.

BRIEF SUMMARY OF THE INVENTION

[0004] An inline gas flow monitoring system is provided which comprises an exhaust tube (herein tube) and an exhaust monitoring apparatus coupled inside the tube, in accordance with some embodiments. In some embodiments, the exhaust monitoring apparatus includes a peripheral support frame, a plurality of sensor tubes, and a circuit board, hi some embodiments, the peripheral support frame includes one or more collector elements extending laterally across the peripheral support frame. In some embodiments, the one or more collector elements each include at least one opening configured to intake gas. In other embodiments, the one or more collector elements each include a plurality of openings configured to intake gas to obtain pressure reading from various regions within the tube. In some embodiments, the tube has a circular cross section, where the one or more collector elements span across the tube. In some embodiments, a pair of collector elements may be vertically separated, i.e., a longitudinal axis of the tube. The one or more collector elements may be arranged along a diameter to obtain a pressure profile measurement across a diameter of the tube. In some embodiments, the one or more collector elements include a first plurality of openings along a direction that is parallel to the longitudinal axis of the tube, and a second plurality of openings along the same direction. In other embodiments, the one or more collector elements include a first plurality of openings along a direction parallel to the longitudinal axis of the tube. In some embodiments, the one or more collector elements include a second plurality of openings along a direction orthogonal to the longitudinal axis of the tube.

1(1(105] In some embodiments, the circuit board includes a plurality of pressure sensors that are coupled to the one or more openings in the one or more collector elements. Tn some embodiments, the pressure sensors arc absolute pressure sensors. In other embodiments, the pressure sensors are differential pressure sensors. In some embodiments, the pressure sensors may include a plurality of nozzles to facilitate pressure measurement from different locations in the collector element. In some embodiments, the circuit board may include a transmitter circuitry to transmit readings from the plurality of pressure sensors to a compute device connected externally to the exhaust monitoring apparatus.

[0006] The exhaust monitoring apparatus may be utilized to measure gas properties in the exhaust tube, in accordance with some embodiments. In some embodiments, a method utilized includes intaking a gas through a first opening in a first collector element and a second opening in a second collector element of the exhaust monitoring apparatus. The first collector element and a second collector clement arc separated by a distance within the exhaust tube. The method further includes transporting the gas from both the first opening and the second opening to one or more pressures sensors located within the exhaust tube. In some embodiments, the method further includes utilizing a first sensor tube to transport the gas from the first opening to the one or more pressure sensors. In some embodiments the method further includes utilizing a second sensor tube to transport the gas from the second opening to the one or more pressure sensors. The method further includes measuring, by the one or more pressure sensors, a first pressure within the first sensor tube. The method further includes measuring, by the one or more pressure sensors, a second pressure within the second sensor tube. The method further includes outputting a pressure reading at least partially based on the first pressure and the second pressure measured by the one or more pressure sensors. In some embodiments, the method further includes computing a flow velocity based on the first pressure, the second pressure, and a predetermined value of a density of the gas. While the examples here are primarily directed to gas exhaust monitoring, this does not preclude the exhaust monitoring apparatus to be used in other applications.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The material described herein is illustrated by way of example and not by way of limitation in the accompanying figures. For simplicity and clarity of illustration, elements illustrated in the figures arc not necessarily drawn to scale. For example, the dimensions of some elements may be exaggerated relative to other elements for clarity. Also, various physical features may be represented in their simplified “ideal” forms and geometries for clarity of discussion, but it is nevertheless to be understood that practical implementations may only approximate the illustrated ideals. For example, smooth surfaces and square intersections may be drawn in disregard of finite roughness, comer-rounding, and imperfect angular intersections characteristic of structures formed by nanofabrication techniques. Further, where considered appropriate, reference labels have been repeated among the figures to indicate corresponding or analogous elements.

[0008] Figure 1A illustrates a schematic of a substrate processing system, where a plurality of exhaust lines is coupled with an exhaust or a house vacuum system, in accordance with an embodiment of the present disclosure.

[0009] Figure IB is an illustration of an isometric view of an apparatus designed to measure gas properties, in accordance with an embodiment of the present disclosure.

[0010] Figure 1C is an illustration of an isometric view of a support frame utilized in the apparatus in Figure IB, in accordance with an embodiment of the present disclosure.

[0011] Figure ID is an illustration of a portion of a collector element of the support frame illustrated in Figure 1C, in accordance with an embodiment of the present disclosure.

[0012] Figure IE is an illustration of a portion of a collector element of the support frame illustrated in Figure 1C, in accordance with an embodiment of the present disclosure.

[0013] Figure IF is an enhanced isometric illustration of a portion of the apparatus in Figure 1 A, in accordance with an embodiment of the present disclosure.

[0014] Figure 1G is an enhanced isometric illustration of a portion of the apparatus in Figure 1A, in accordance with an embodiment of the present disclosure.

[0015] Figure 2A is an illustration of the apparatus in Figure 1A, illustrating a mechanical coupling between a circuit board and a support frame of the apparatus, in accordance with an embodiment of the present di closure.

[0016] Figure 2B is an illustration of the circuit board in Figure 2A, where the circuit board is encased in a protective housing, in accordance with an embodiment of the present disclosure. [0017] Figure 3A is an illustration of a tube, in accordance with an embodiment of the present disclosure.

[0018] Figure 3B is an illustration of the apparatus in Figure IB coupled inside the tube illustrated in Figure 3A, in accordance with an embodiment of the present disclosure.

[0019] Figure 3C is a plan-view illustration of the structure in Figure 3B, in accordance with an embodiment of the present disclosure.

[0020] Figure 3D is a flow chart illustrating a method of measuring gas pressure in the apparatus of Figure 3B, in accordance with an embodiment of the present disclosure.

[0021] Figure 3E is an illustration of pressure measurement using the apparatus in Figure 3B, in accordance with an embodiment of the present disclosure.

[0022] Figure 3F is an illustration of pressure measurement using the apparatus in Figure 3B, in accordance with an embodiment of the present disclosure.

[0023] Figure 3G is an illustration of pressure measurement using the apparatus in Figure 3B, in accordance with an embodiment of the present disclosure.

[0024] Figure 3H is an illustration of pressure measurement using the apparatus in Figure 3B, in accordance with an embodiment of the present disclosure.

[0025] Figure 31 is a flow chart illustrating a method of measuring gas pressure in the apparatus of Figure 3B, in accordance with an embodiment of the present disclosure. [0026] Figure 4A illustrates a simplified schematic of the structure in Figure 3B, including a damper, in accordance with an embodiment of the present disclosure.

[0027] Figure 4B illustrates a schematic of a substrate processing system, where each exhaust line in the plurality of exhaust lines includes a damper, in accordance with an embodiment of the present disclosure.

[0028] Figure 5 illustrates a block diagram of a controller system, in accordance with an embodiment of the present disclosure.

[0029] Figure 6 illustrates a processor system with machine readable storage media having instructions that when executed cause the processor to measure and report gas properties, in accordance with various embodiments.

DETAILED DESCRIPTION

[0030] The material described herein is illustrated by way of example and not by way of limitation in the accompanying figures. For simplicity and clarity of illustration, elements illustrated in the figures are not necessarily drawn to scale. For example, the dimensions of some elements may be exaggerated relative to other elements for clarity. Also, various physical features may be represented in their simplified “ideal” forms and geometries for clarity of discussion, but it is nevertheless to be understood that practical implementations may only approximate the illustrated ideals. For example, smooth surfaces and square intersections may be drawn in disregard of finite roughness, comer-rounding, and imperfect angular intersections characteristic of structures formed by nanofabrication techniques. Further, where considered appropriate, reference labels have been repeated among the figures to indicate corresponding or analogous elements.

[0031] An intelligent exhaust gas monitoring apparatus is described. n the following description, numerous specific details are set forth, such as structural schemes, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to one skilled in the art that embodiments of the present disclosure may be practiced without these specific details. In other instances, well-known features, such as exhaust equipment operations, are described in lesser detail to not unnecessarily obscure embodiments of the present disclosure. Furthermore, it is to be understood that the various embodiments shown in the Figures are illustrative representations and are not necessarily drawn to scale.

[0032] Tn some instances, in the following description, well-known methods and devices are shown in block diagram form, rather than in detail, to avoid obscuring the present disclosure. Reference throughout this specification to “an embodiment” or “one embodiment” or “some embodiments” means that a particular feature, structure, function, or characteristic described in connection with the embodiment is included in at least one embodiment of the disclosure. Thus, the appearances of the phrase “in an embodiment” or “in one embodiment” or “some embodiments” in various places throughout this specification arc not necessarily referring to the same embodiment of the disclosure. Furthermore, the particular features, structures, functions, or characteristics may be combined in any suitable manner in one or more embodiments. For example, a first embodiment may be combined with a second embodiment anywhere the particular features, structures, functions, or characteristics associated with the two embodiments are not mutually exclusive.

[0033] The terms “coupled” and “connected,” along with their derivatives, may be used herein to describe functional or structural relationships between components. These terms are not intended as synonyms for each other. Rather, in particular embodiments, “connected” may be used to indicate that two or more elements are in direct physical, optical, or electrical contact with each other. “Coupled” may be used to indicated that two or more elements are in either direct or indirect (with other intervening elements between them) physical, electrical or in magnetic contact with each other, and/or that the two or more elements co-opcratc or interact with each other (e.g., as in a cause an effect relationship).

[0034] The terms “over,” “under,” “between,” and “on” as used herein refer to a relative position of one component or material with respect to other components or materials where such physical relationships are noteworthy. Unless these terms are modified with “direct” or “directly,” one or more intervening components or materials may be present. Similar distinctions are to be made in the context of component assemblies. As used throughout this description, and in the claims, a list of items joined by the term “at least one of’ or “one or more of’ can mean any combination of the listed terms.

[0035] The term “adjacent” here generally refers to a position of a thing being next to (e.g., immediately next to or close to with one or more things between them) or adjoining another thing (e.g., abutting it).

[0036] Unless otherwise specified in the explicit context of their use, the terms “substantially equal,” “about equal” and “approximately equal” mean that there is no more than incidental variation between two things so described. In the art, such variation is typically no more than +/- 10% of the referred value.

[0037] Existing exhaust monitoring systems for semiconductor device fabrication tools are bulky and limited in function. Existing exhaust monitoring systems collect data from sensor tubes connected to the exhaust pipes and determine the pressure externally in a computing device that sits outside of the exhaust pipes. The gas pressure is not locally measured within the exhaust pipe but rather a measurement at a peripheral point on the pipe. Cross-sectional measurement of gas pressure is then estimated from the peripheral measurement. There are often significant differences between pressure measurement made along a longitudinal axis and a periphery of the tube. Such differences can often result in overestimation of exhaust system requirements because gas velocity at the periphery cannot accurately describe the gas velocity at the center of the tube. These differences can lead to significant increase in operating costs. Furthermore, existing exhaust pressure monitoring systems lack the capability to measure gas flow velocity, which is important for estimating conductance (for example, air flow volume) of the exhaust pipe. Measurement of conductance can help to determine if existing exhaust pipes are sufficient for enabling requisite flow capacity or whether additional exhaust pipes arc needed.

[0038] To address limitations described above, an in-pipe exhaust monitoring apparatus that can be implemented in exhaust tubes, pipes, or conduits of semiconductor fabrication equipment is disclosed. In accordance with an embodiment of the present disclosure, the exhaust monitoring apparatus includes a peripheral support frame and one or more collector elements coupled with the peripheral support frame. The one or more collector elements can be a customized bar or rod in some embodiments. In some embodiments, the one or more collector elements extend laterally across the peripheral support frame. Tn some embodiments, the one or more collector elements include a plurality of openings configured to intake gas or allow gas to flow through to an attached tube coupled with a sensor (e.g., pressure sensor, temperature sensor, etc.). In some embodiments, a circuit board is coupled with the peripheral support frame. In some embodiments, the circuit board includes a plurality of pressure sensors coupled to the one or more collector elements and a transmitter (e.g., a transmitter circuitry) to transmit readings from the plurality of pressure sensors. In some embodiments, the circuit board may include one or more flow sensors in addition to pressure sensors.

[0039] In some embodiments, the exhaust monitoring apparatus may further include a separate movable damper that is coupled within the tube. In some embodiments, the damper may actively control the total air flow within the tube. In some embodiments, the readings from the pressure sensor may be transmitted, via a wired connection, or wirelessly, to control the damper to increase (if previous setting is not at maximum flow) or to reduce an overall air flow.

[0040] A semiconductor fabrication equipment such as an etch or deposition tool, for example, can include a large number of exhaust tubes. Tire exhaust tubes may be coupled with various chambers within the tool (process chambers, vacuum transfer chambers, Equipment Front End Module (EFEM), etc.). Exhaust tubes from different parts of the tool may be coupled into a unified exhaust or to different sub-exhaust systems that feed into a unified exhaust. In some cases, exhaust tubes may feed into different systems some of which require exhaust and some that may not. The exhaust tubes may have the same or different cross-sectional areas and may be designed to accommodate a throughput that depends on the volume of gas pumped. In some embodiments, the flow rates within different sub-exhaust tubes may be individually programmed to increase efficiency. The damper of the exhaust monitoring system in some embodiments may be incorporated in one or more exhaust tubes and may be controlled to increase airflow throughput, efficiency, and uniformity across different tubes or all of the above. [0041] Figure 1A illustrates a schematic of a substrate processing system 100 including one or more exhaust monitoring apparatus 101 within exhaust system 103, in accordance with an embodiment of the present disclosure. In the illustrative embodiment, exhaust system 103 is coupled to process tool 105. In some examples, exhaust system 103 may be referred to as a house vacuum system 103. Tn some embodiments, exhaust system 103 includes a plurality of exhaust lines (e.g., exhaust lincsl07A-107F), and each exhaust line includes an exhaust monitoring apparatus 101. Details of the exhaust monitoring apparatus 101 will be described herein.

[0042] In some embodiments, exhaust lines 107A-107F (collectively “exhaust lines 107”) may be exhaust tubes that are coupled between different components within process tool 105 and an exhaust reservoir 109. For example, process tool 105 may include at least one processing chamber 105A (e.g., processing modules), transfer chamber 105B (e.g., vacuum transfer modules or VTM), equipment front-end module 105C (or EFEM 105C), and a gas box 105D. In the illustrative embodiment, exhaust line 107A is coupled with process chamber 105 A, exhaust lines 107B, 107C, and 107D are coupled with transfer chamber 105B, exhaust line 107E is coupled to EFEM 105C, and exhaust line 107F is coupled to gas box 105D.

[0043] It may be desirable to maintain a requisite flow within a respective exhaust line 107A-107F. Physically each exhaust line 107A-107F may have a different throughput requirement which can be satisfied by changing the dimensions of the tubes, for example. In some embodiments, insertion of a damper (not shown), within each exhaust monitoring apparatus 101 may enable the exhaust system 103 or house vacuum system 103 to operate more efficiently.

[0044] In some embodiments, a total gas flow in the exhaust system 103 may be monitored and controlled by individual exhaust monitoring apparatus 101 in respective exhaust line 107 A- 107F. In some embodiments, dampers in each exhaust line 107A-107F may be controlled individually by external controller 111. In some embodiments, external controller 111 may communicate with a respective transmitter within one or more exhaust monitoring apparatus 101 to rotate a respective damper to alter gas flow. In some embodiments, controller 111 may control other substrate processing systems besides substrate processing system 100. In some embodiments, the exhaust monitoring apparatus 101 may communicate with other exhaust monitoring systems in other substrate processing tools directly (or indirectly through an intermediate device such as controller 111.) In some embodiments, a centralized system may be configured to monitor and/or control gas exhaust in a fleet of substrate processing tools via one or more exhaust monitoring apparatus 101 or controller 111.

[0045] Figure IB illustrates an isometric illustration of exhaust monitoring apparatus 101, according to some embodiments. Exhaust monitoring apparatus 101 is designed to be installed within an exhaust tube/pipe to measure properties of inline air flow, in accordance with some embodiments. As such, in the illustrative embodiment, exhaust monitoring apparatus 101 includes peripheral support frame 102 and one or more collector elements, such as collector element 104 coupled or connected with peripheral support frame 102. As shown, in some embodiments, collector element 104 extends laterally across an upper portion of peripheral support frame 102. In some embodiments, collector element 104 includes a plurality of openings 106 and 108. Structural details of plurality of openings 106 and 108 are further described in Figures ID and IE. In some embodiments, a single opening 106 and a single opening 108 may be adequate. However, a plurality of openings 106 and 108 can provide measurements across different points. The plurality of openings 106 and 108 extend through the collector element 104 and arc designed for interfacing with sensor tubes (c.g., via insertion) and to intake gas. As shown, a sensor tube 110A is coupled with collector element 104 through opening 106.

[0046] In some embodiments, a circuit board 112 is coupled with a support panel 130 of peripheral support frame 102. In the illustrative embodiment, circuit board 112 includes at least one pressure sensor, such as pressure sensor 1 14 coupled to collector element 104 via sensor tube 110A. In an embodiment, circuit board 112 further includes transmitter 126 to transmit readings from pressure sensor 114 to another device (e.g., controller 111 in Figure 1A, a computer, or another centralized control or monitoring system). In some embodiments, circuit board 112 may include at least one air flow sensor in addition to pressure sensor 114. In some embodiments, a temperature sensor may also be included. [0047] Figure 1C illustrates an isometric illustration of peripheral support frame 102, in accordance with an embodiment of the present disclosure. The circuit board 112 and sensor tubes are not illustrated in Figure 1C. The support panel 130 for mounting a circuit board is visible in the illustration.

[0048] In an embodiment, peripheral support frame 102 includes an upper ring structure 116 (herein ring structure 116). In the illustrative embodiment, ring structure 116 is circular. As shown, collector element 104 extends across a diameter of the ring structure 116. In other embodiments, ring structure 1 16 can be elliptical, square, rectangular, or other shape that would allow proper interfacing with an airflow pipe. Placement of collector clement 104 across a diameter advantageously enables a radial profile of pressure and flow measurements. In some embodiments, the number of openings 106 or 108 depends on a diameter, DR, of ring structure 116 as well as on a diameter of opening 106. In some embodiments, DR ranges between 3 inches and 9 inches. In other embodiments, DR is at least 9 inches but less than 18 inches. In some embodiments, the number of openings 106 also depends on the number of measurement locations desired. In some embodiments, the number is between 2 and 4. In other embodiments, number of openings 106 is greater than 4. In the illustrative embodiment, the number of openings 106 exceeds the number of openings 108. Tn other embodiments, the number of openings 108 exceeds the number of openings 106. In an exemplary embodiment, one of the openings 106 is located at an axial center of peripheral support frame 102. An opening 106 at an axial center would facilitate detection of airflow at a maximum pressure (and maximum flow velocity) as will be discussed below. In the illustrative embodiment, collector element 104 includes both openings 106 and 108. Openings 108 are designed to provide measurement of a component of gas flow. Differences in measurement values between those obtained utilizing openings 106 and 108 can be used for calibration of one or more pressure sensors. Openings within collector element 104 and 120 will be described in further detail in relation to portions 117 below.

[0049] Figure ID illustrates an enhanced isometric illustration of portion 117 of collector element 104 in Figure 1C. The plurality of openings such as openings 106 A, 106B and 106C have an orientation that is parallel to the longitudinal axis (along the Z-direction) of peripheral support frame 102. In some embodiments, openings 106A and 106B extend from a top surface 104A to a bottom surface 104B. As shown, openings 106A and 106B extend across a vertical thickness, Ti, of the collector element 104. Ti spans a distance between the top surface 104A to a bottom surface 104B . Tn general , a lower end of opening 106 A i s configured to intake gas and an upper end of opening 106A is configured to couple to a sensor tube (not shown). However, the placement of a sensor tube is dependent on a direction of gas flow as will be discussed below (in Figure 3E). In the illustrative embodiment, openings 106A and 106B are circular and have a diameter, Di, between 1 mm to 10 mm. In some embodiments, Di is substantially uniform over the vertical thickness Ti.

[0050] In the illustrative embodiment, openings 106A, 106B and 106C arc spaced apart by a distance, Si, along the diameter (along the X-direction). In some embodiments, adjacent openings 106A, 106B and 106C are equidistant from one another. For example, openings 106A and 106B are spaced apart by a distance, Si, and openings 106B and 106C are also spaced apart by a distance, Si. Si may be between 0.2 cm and 10 cm. In some embodiments, spacings between adjacent pairs of openings (e.g., 106A and 106B, and 106B and 106C) may not be uniform. The placement of openings 106A, 106B and 106C within portion 117 may be designed for measurement at a specific location within a housing where the exhaust monitoring apparatus 101 may be housed. In the illustrative embodiment, opening 106A may be at an axial center of collector 104 (along z-direction).

[0051] In some embodiments, openings 108A, 108B and 108C have an orientation that is orthogonal (along the Y-direction) to the longitudinal axis of the peripheral support frame 102. Tn some embodiments, plurality of openings 108 extend from a sidewall surface 104C to sidewall surface 104D. As shown, opening 108A extends across a lateral thickness, Ti, of collector element 104. A first end of opening 108A is configured to intake gas and an opposite of opening 108A is configured to couple to a sensor tube (not shown). However, the placement of a sensor tube is dependent, at least partially, on a direction of gas flow as will be discussed below (in Figure 3E). In the illustrative embodiment, openings 108A and 108B are circular and have a diameter, Di. Di may be between 1 mm and 10 mm. In some embodiments, Di is substantially uniform over the lateral thickness Ti. In some embodiments, D2 and Di are substantially equal. [0052] In the illustrative embodiment, openings 108A, 108B and 108C are spaced apart by a distance, S2, along the diameter (along the X-direction). Tn some embodiments, adjacent openings 108A, 108B and 108C are equidistant from one another. For example, openings 108A and 108B arc spaced apart by a distance, S2, and openings 108B and 108C arc also spaced apart by a distance, S2. S2ma be between 0.2 and 10 cm. In some embodiments, spacings between adjacent pairs of 108 openings (e.g., 108A and 108B, and 108B and 108C) may not be uniform. The placement of openings 108A, 108B, and 108C within portion 1 17 may be designed for measurement at a specific location within a housing where the exhaust apparatus may be housed in.

[0053] A minimum spacing between opening 108A and an adjacent opening 106B or 106C is a spacing that prevents intersection. In some embodiments, the spacing is at least 1 mm. In others it can be less than 1 mm but greater than 0.1 mm. An arrangement where a vertical opening such as opening 106 A is placed between a pair of lateral openings, for example, openings 108C and 108B, ensures that vertical openings do not intersect with lateral openings. As such a minimum spacing between 1mm but greater than 0.1 mm is sufficient to prevent intersection between vertical openings and lateral openings.

[0054] Tn Figure ID, Ti is substantially uniform over the vertical thickness Ti. Tn other embodiments, collector clement 104 has a top surface 104A that is wider than a bottom surface 104B as illustrated in structure 119 in Figure IE. Structure 119 has one or more properties of portion 117 of the collector element 104 (illustrated in Figure ID), such as lateral openings 108 and vertical openings 106. Structure 119 has a narrower bottom surface 104B compared to top surface 104A, which advantageously reduces a total cross-sectional area of the bottom surface 104B. A reduced total cross- sectional area of bottom surface 104B reduces net gas impedance within a tube that houses the peripheral support frame. In some embodiments, the bottom surface 104B has an area that is about 25%-65% less than an area of top surface 104A. As shown, bottom surface 104B has a lateral thickness, T3, that is less than the lateral thickness T2 of the top surface 104A. In some embodiments, T3 is substantially equal to or greater than diameter, Di, of openings 106A and 106B.

[0055] In some embodiments, peripheral support frame 102 may include more than one collector element to facilitate flow rate measurements as well as pressure measurements at multiple locations along a direction of gas flow. Referring again to Figure 1C peripheral support frame 102 further includes a pair of vertical support columns 118A and 118B (herein support columns 118A and 118B) on opposite ends of the diameter of ring structure 116. In some embodiments, support columns 1 18 A and 1 18B extend away from circular ring structure 1 16. In some embodiments, an additional collector clement 120 is coupled with support columns 118 A and 118B, as shown.

[0056] In some embodiments, collector element 120 has one or more features of collector element 104 described in association with (Figures ID and IE). In the illustrative embodiment, collector element 120 has one or more features of collector element 104 (described in association with Figure IE), such as vertical and lateral thickness, shapes etc. In other embodiments collector element 120 can have different vertical and lateral thicknesses, Ti and T2, respectively, compared to collector element 104. In some embodiments, collector element 120 includes a plurality of openings 122 and 124. In exemplary embodiments, plurality of openings 122 are spatially arranged substantially identical to plurality of openings 106. In some embodiments, plurality of openings 124 arc spatially arranged substantially identical to plurality of openings 108. In some embodiments, collector element 104 may be above and parallel to the collector element 120, as shown. Collector element 120 may be located below collector element 104 to provide pressure measurements at approximately same radial locations, though separated along a longitudinal axis (z-axis in the Figure 1C). Measurement of pressure at a same radial location is prcfcrrablc to obtain a measurement of flow velocity that is substantially parallel to the longitudinal axis. When collector element 104 is above and parallel to collector element 120, as shown, a net impedance to gas flow across a length (along Z-direction) of peripheral support frame 102 may also be reduced.

[0057] In some embodiments, collector elements 104 and 120 are vertically separated from each other by a distance S3. In some embodiments, S3 is between 5 cm and 100 cm. In some embodiments, S3 is between 15 cm and 30 cm. In some such embodiments, circuit board 112 would remain as shown in Figure IB regardless of a length of S3. The sensor tube 110B would be shortened or extended to reach collector element 120, as shown in Figure IB. Referring to Figure 1C, in embodiments, S3 can depend on the diameter DR. In some embodiments, a larger DR can corelate with a greater S3. A DR that ranges between 3 inches and 9 inches may corelate with an S3 in range of 5 cm to 50 cm. A DR that ranges between 9 inches to 18 inches may correlate with an S3 in range of 50 cm to 100 cm. In other embodiments, a DR that ranges between 3 inches and 9 inches can corelate with an S3 in range of 5 cm to 100 cm.

[0058] In some embodiments, peripheral support frame 102 may be fabricated out of a polymer such as polyvinyl chloride (PVC). In an embodiment, the design of peripheral support frame 102 may be drawn and may be 3D printed. In some embodiments, peripheral support frame 102 further includes a plurality of flaps 132 laterally extending from ring structure 116. Four flaps are shown, though the number of such flaps 132 may vary with the diameter of ring structure 116. Each of flaps 132 include a respective opening 134 for securing the ring structure 116 to a tube (as discussed herein). In some embodiments, peripheral support frame 102 has two flaps. In some embodiments, peripheral support frame 102 has three flaps. In some embodiments, peripheral support frame 102 has more than four flaps.

[0059] In the illustrative embodiment, support columns 118 A and 118B further include a respective opening 136 that facilitates a measurement of the gas pressure by an external pressure measurement tool, as will be described below. Opening 136 may be circular as shown. Opening 136 may have a diameter between 1 mm and 10 mm, in accordance with some embodiments. [0060] Figure IF illustrates an enhanced isometric illustration of a portion 125 of exhaust monitoring apparatus 101 in Figure IB. In an embodiment, sensor tube 110A is coupled between opening 106C and first nozzle 114A of pressure sensor 114. In some embodiments, pressure sensor 114 is a differential pressure sensor. In some embodiments, differential pressure sensor 114 measures pressure differences between two different points along a path of a gas flow. The two points may be at two different collectors such as collector clement 104 and collector element 120 (as shown in Figure IB). Differential pressures may be measured by pressure sensor 114 using sensor tubes 110A and 110B. In the illustrative embodiment, sensor tube 110B is coupled between a second nozzle 1 14B of pressure sensor 1 14 and an opening in collector element 120 (not visible in Figure IF but visible in Figure 1 , for example).

[0061] Gas entering sensor tubes 110A and 110B along a flow direction (z-dircction in Figure IF) can be used to estimate the flow speed using the differential pressure and gas density. A flow rate can be computed from flow speed and a flow cross sectional area without a need for a flowmeter (See Figure 3C). A plurality of sensing points in collector elements 104 in conjunction with two or more differential sensors can also be used to obtain a gas velocity profile. A gas velocity profile may be utilized to improve flow rate computational accuracy. [0062] In some embodiments, differential pressure sensors use Bernoulli’s equation to measure the flow of gas in a tube. Differential pressure sensors introduce a constriction in a tube that creates a pressure drop across two points within the tube. The pressure drop is a difference in the pressure between an upstream side and a downstream side of the differential pressure sensor. When flow increases, a larger pressure drop is created. Impulse piping routes upstream and downstream pressures of the differential pressure sensors to manometer tubes that measure the difference in pressure in the upstream and in the downstream sides of the restriction. A difference in the measured pressure (i.e., differential pressure) is used to determine the flow rate. In other embodiments, pressure sensor 114 is an absolute pressure sensor. Unlike a differential pressure sensor, an absolute pressure sensor measures a pressure at a single point relative to a calibrated vacuum level. In the illustrative embodiment, sensor tubes 110A and 110B provide measurement of pressure at two points at two different collector locations. It is to be appreciated that sensor tubes 1 10A and 1 10B may each have a length that is different without adversely affecting the accuracy of the measurements. In some embodiments, lengths of various sensor tubes may differ by up to 50%.

[0063] Figure 1G illustrates an enhanced isometric illustration of portion 127 of exhaust monitoring apparatus 101 in Figure IB. In an illustrative embodiment, sensor tube HOC is coupled between opening 124A of collector element 120 and nozzle 128A of pressure sensor 128. In other examples, sensor tube 110C can be coupled between an upper end (hidden) of opening 122A and nozzle 128 A of pressure sensor 128.

[0064] As shown, a sensor tube 1 10C is connected to a back side of opening 124A. In some embodiments, pressure sensor 128 is a differential pressure sensor. In other embodiments, pressure sensor 128 is an absolute pressure sensor. It is to be appreciated that sensor tube HOC may have a different length compared to lengths of sensor tubes 110A and 110B (in Figure IF). Calibration between the different sensor tubes (e.g., 110A, 110B and 110C) may be performed by coupling to a same opening, but to different pressure sensors, as will be discussed below in Figure 3H.

[0065] Figure 2A illustrates an isometric illustration of exhaust monitoring apparatus 101 of Figure IB according to some embodiments of the present invention. Figure 2A is an isometric illustration of a back side of exhaust monitoring apparatus 101. As shown, the circuit board is mounted on support panel 130 of peripheral support frame 102. In the illustrative embodiment, support panel 130 includes a pair of extensions 130A and 130B that arc coupled with ring structure 116. Extensions 130A and 130B are designed to provide mechanical support for circuit board 112 and include a same material as the material of the peripheral support frame. As shown, circuit board 1 12 is positioned within ring structure 1 16 to prevent elements of circuit board 1 12 from contacting a tube that the peripheral support frame 102 is designed to be housed in.

[0066] The exhaust monitoring apparatus 101 is designed to operate in environments for measuring gas properties of corrosive by products. As such, it is desirable that circuit board 112 and elements within, such as pressure sensor 114 and wireless transmitter 126, be protected from corrosive byproducts that exhaust monitoring apparatus 101 can be exposed to during operation. [0067] Figure 2B is an isometric illustration of an exhaust monitoring apparatus 200 that has all the properties of exhaust monitoring apparatus 101 (in Figure 2A). Figure 2B shows that circuit board 112 in Figure 2A is encased in resin 202. In some embodiments, resin 202 may include a polymer coating that has insulative properties and is non-reactive with corrosive gases. Resin 202 may be up to 1 millimeter thick, in accordance with some embodiments.

[0068] Figure 3A is an isometric illustration of tube structure 300 (e.g., an exhaust pipe or tube) designed to retrofit an apparatus such as exhaust monitoring apparatus 101 (described in association with Figures 1A-1F). As shown, tube structure 300 includes cylindrical tube 302. In some embodiments, tube 302 has a circular cross section to permit laminar flow for optimal gas flow. Depending on application, tube 302 may have a diameter that is between 2 inches and 10 inches. In some embodiments, tube structure 300 further includes a mounting frame 304 attached to an end 308 of tube 302. In some embodiments, mounting frame 304 is designed to couple to an apparatus (such as for example exhaust monitoring apparatus 101 described above). In some embodiments, mounting frame 304 includes a plurality of bolt holes 306 to facilitate coupling with exhaust monitoring apparatus 101 (described above). In an embodiment, when tube 302 includes a metallic construction, mounting frame 304 may be welded on to the external surface of tube 302. In other embodiments, regardless of the material of tube 302, mounting frame 304 is fabricated as part of tube structure 300. Tube 302 may further include at least an opening, such as opening 307, to measure pressure at a periphery of the tube. One end of a sensor tube (not shown) may be attached to the opening 307 and another end may be attached to a pressure sensor located external to tube 302. In the illustrative embodiment, tube 302 includes two openings 307 that are substantially diametrically separated. In such embodiments, openings 307 can facilitate a simultaneous pressure measurement at two substantially diametrically opposite ends of tube 302. [0069] Figure 3B is an isometric illustration of apparatus 320 including exhaust monitoring apparatus 101 coupled with tube structure 300 at end 308. Apparatus 320 may be an example of an inline gas monitoring system that is designed to measure velocity of gas from an exhaust of a substrate processing system (such for example substrate processing system 100). In the illustrative embodiment, ring structure 1 16 of exhaust monitoring apparatus 101 is circular and seated on mounting frame 304. As shown, individual ones of flaps 132 of exhaust monitoring apparatus 101 are secured to a respective bolt hole 306 (not visible in the Figure) using bolt 309. In some embodiments, support columns 118A and 118B are confined within ring structure 116. In an embodiment, openings 136 within support columns 118A and 118B are aligned with opening 307 (as shown in Figure 3A) in tube 302. Alignment between openings 136 and 307 facilitates an external measurement of gas pressure in tube 302 during operation. An external pressure measurement tool, such as an absolute pressure sensor, may be coupled through a tube to opening 307. Gas flowing into opening 136 in the respective support columns 118A and 118B may be channeled by a respective tube to a respective absolute pressure sensor. The measurement of pressure in the vicinity of openings 136 by a measurement tool that is distant from opening 136 constitutes an external measurement of gas pressure in tube 302. It is to be appreciated that support columns 118A and 118B may be in contact with side walls of tube 302. As such, surfaces of support columns 118A and 118B may match a curvature of tube 302. Matched curved surfaces between support columns 1 18 A and 1 18B and tube 302 can enable a flush contact with no gaps. In some embodiments, opening 136 and 307 may be circular, where a diameter of opening 136 is less than a diameter of opening 307. A smaller diameter can ensure that an external tube can be fixed with no gaps to prevent loss of gas from opening 307.

[0070] In some embodiments, ring structure 116 has an inner diameter Di, that is the same or substantially the same as the inner diameter. Dr, of tube 302. In some embodiments, when Diis greater than or equal to DT then ring structure 116 does not impede gas flow, even though collector elements 104 and 120 themselves partially impede gas flow.

[0071] In embodiments where Diis less than Dr, support columns 118A and 118B may not be in contact with side walls of tube 302. In some such embodiments, an external tube coupled with an absolute pressure sensor will protrude within an inner portion of tube 302.

[0072] Figure 3C illustrates a plan view cross section of apparatus 330. Apparatus 330 is an example of the inline gas monitoring system (Figure 3B) that further includes a plurality of sensor tubes (such as sensor tubes 110A, 110B etc). As shown, tube 302 has a cross sectional area, Ar within an inner sidewall 302A of tube 302. As shown, collector element 104 has an area ACE, and support panel 130 has an effective surface area Asp. Gas flow within the tube 302 is impeded by the presence of collector clement 104 and support panel 130 for the circuit board (not visible) and sensor tubes (e.g., 110A and HOB).

[0073] An open area for gas to flow through tube 302 is given by a difference between AT and sum of ASP and ACE as well as effective surface areas of the sensor tubes (e.g., 110A, 110B etc.). It is desirable for ACE to be as small as possible to facilitate collection of flow data but large enough to be physically rigid. It is to be appreciated that collector element 104 has a substantially same plan- view cross sectional area as collector element 120 (not visible in the figure) to minimize any reduction in gas flow through tube 302. Collector element 120 is directly below collector element 104 to provide pressure measurements at same radial locations (though separated along a longitudinal axis - orthogonal to the plane of the figure). Measurement of pressure at a same radial location may be preferrable to obtain a flow velocity measurement. When collector element 120 is offset relative to collector element 104, then overall flow reduction can be larger, as the difference of open area. AT- (ASP + ACE) is reduced. However, in some embodiments collector clement 120 is offset relative to collector element 104 by up to distance equivalent to half an inner diameter (DT in Figure 3B) of the tube 302.

[0074] Support columns 118A and 118B are not visible and are directly under collector element 104. In exemplary embodiments, support columns 118A and 118B do not increase cross sectional area beyond the collector element 104.

[0075] It is to be appreciated that the presence of exhaust monitoring apparatus 101 within tube structure 300 impedes gas flow by less than 5% under steady state flow turbulent flow conditions. The reduction of gas flow is also a function temperature of the gas. However, for gas temperatures less than 25 degrees Celsius, a less than 5% flow reduction may be observed. [0076] Figure 3D is method 340 of measuring gas pressure in an apparatus such as exhaust monitoring apparatus 101.

[0077] Method 340 begins at operation 341 by flowing gas into tube, where the flowing causes the gas to enter a first end of an opening of a collector element of an exhaust monitoring apparatus within the tube. Method 340 continues at operation 342 by forcing the gas which enters the opening, to be directed into a sensor tube coupled at a second end of the opening. The second end is opposite to the first end. The gas flow is maintained in the sensor tube by a positive pressure from the gas flowing in the tube. The gas is directed to a pressure sensor. The method 340 concludes at operation 343 by using the pressure sensor to make a measurement of pressure of the gas flowing in the sensor tube.

[0078] Figure 3E is a schematic illustrating operation of apparatus 350 including exhaust monitoring apparatus 101 within tube 302 described in association with Figure 3B, according to some embodiments. In an embodiment, exhaust gas, for example gas 351 (indicated by arrows) flows within tube 302 and enters one or more openings in collectors 120 and 104. In some embodiments, gas 351 passes through opening 122 A of collector 120, into an inlet of sensor tube HOC and is directed to pressure sensor 128. A positive pressure within tube 302 maintains the flow of gas 351 in the positive y-direction in the sensor tube 110C. The positive pressure ensures that some of gas 351 which flows into one end 352 of opening 122A continues to flow into sensor tube HOC coupled to an opposite end 353 of opening 122A. Pressure sensor 128 senses gas 351 striking a sensing element within and measures a pressure of gas 351 within tube 1 10C. Because sensor 128 is close to opening 122A, opening 122A is the approximate measurement location. In an embodiment, a dynamic measurement (or a real time continuous measurement) of gas pressure by pressure sensor 128 is facilitated because there is continual flow of gas 351 in sensor tube 110C. In an embodiment, a continual flow within sensor tube 110C is established because gas 351 exits the pressure sensor 128 through an opening within (that is not shown). [0079] Gas 351 also passes through the opening 106A in collector element 104, into an inlet of sensor tube 110A and is directed to pressure sensor 114. Gas 351 flows into one end 354 of opening 106A into sensor tube 1 10A that is coupled to an opposite end 355 of opening 106A. A positive pressure within the tube 302 ensures that gas 351 continues to flow within sensor tube 110A. Pressure sensor 114 senses gas 351 striking a sensing element within and measures pressure of gas 351 flowing within sensor tube 110A. Because pressure sensor 114 is close to opening 106A, opening 106A is the approximate measurement location. In an embodiment, a dynamic measurement (or a real time continuous measurement) of gas pressure at pressure sensor 114 is facilitated as long as there is continual flow of gas 351 in the tube 110A. A continual flow is established because gas 351 exits the pressure sensor 114 through an opening within (that is not shown). In an exemplary embodiment, openings 106A and 122A are located at an axial center of exhaust monitoring apparatus 101. Openings at an axial center of collector elements 104 and 120 can enable detection of a maximum pressure of gas 351 flowing within tube 302. In embodiments where there is laminar flow in tube 302 that is cylindrical, a maximum flow velocity of gas 351 is at an axial center of cylindrical tube 302. In some such embodiments, a maximum flow velocity corelates to a maximum pressure.

[0080] In the illustrative embodiment, both openings 106 A and 122 A are oriented along a same direction (z-direction). This enables pressure sensors 114 and 128 to measure a component of gas 351 flowing in substantially the same direction (for c.g., z-dircction in the Figure). Vertical spacing, S3, between collector element 120 and collector element 104 may be sufficient to permit a substantially vertical component of gas 351 to enter opening 106A. As discussed above, S3 can be a function of diameter of tube 302 (DT in Figure 3B).

[0081] In the illustrative embodiment, openings 106 A and 122 A are a representative pair of openings in collector elements 104 and 120, respectively. As shown, openings 106A and 122A are vertically or substantially vertically aligned. In some such embodiments, other pairs of openings along the collector elements 104 and 120, that are not at an axial center (for example 122AB and 106AB - not shown), are also aligned vertically or substantially vertically. A vertical alignment between respective openings in a collection of openings 106 in collector element 104 and respective openings in a collection of openings 122 in collector element 120 (such as is illustrated in Figure 1C) can help provide a correlated pressure measurement for a collection of a pair of openings that are separated by a same distance S3. Such correlated pressure measurements can help provide a profile of pressure measurements along a diameter of tube 302. [0082] A difference in pressure between openings 122A and 106A can enable measurement of gas flow velocity. A difference in pressure measurement between pressure sensor 128 and 114, coupled to openings 122A and 106A, respectively, can be directly used to compute flow velocity. In some embodiments, the computation can be done by the circuit board 112. In some embodiments, the data from each pressure sensor 128 and 1 14 can be transmitted to a computer external to the tube 302 for flow velocity calculation. In some embodiments, the detected difference in pressure measurement can be utilized to compute a flow velocity based on the equation (1) below:

[0083] V² =2[P₂-Pi]/rho, (1) [0084] Where V is flow velocity, Pi and P2 are pressure readings at opening 122A and 106A, respectively, and rho is a density of gas (or weighted density of different gas components) flowing in tube 302. Tn one example, the density of nitrogen at standard temperature and pressure (STP) may be utilized in the calculation. In an embodiment, the velocity is an average flow velocity computed between opening 122 A and 106 A.

[0085] In some embodiments, a gas flow velocity may be obtained from a test set up where tube 302 may be attached, at a base, to a fan capable of generating flow of a calibration gas (e.g., N2 or air). The flow speed of the calibration gas can be varied to help measure a range of flow velocities for a given tube size. The flow velocity information can be utilized to implement a correct fan size (for example fan speed for enabling a certain cubic flow per minute of gas) for enabling gas flow. Estimating an accurate fan size can eliminate unnecessary implementation of larger exhaust fans in gas exhaust lines in systems such as those illustrated in Figure 1A. Accurate estimation can help reduce cost, prevent long maintenance down times and save space in systems where a smaller, instead of a larger, exhaust fan can be utilized.

[0086] In some embodiments, sensor tube HOD may be coupled to lateral opening 124A within collector element 120 as illustrated in Figure 3F. In some such embodiments, gas 351 enters along lateral opening 124A at end 356 and enters tube 1 10D at end 357. The method of pressure measurement is substantially identical to the method of pressure measurement described in association with Figure 3E. In some such embodiments, a transverse flow velocity (along y- direction) of gas 351 may be computed by measuring pressure at opening 124A.

[0087] In some embodiments, sensor tube 110A may be coupled with second nozzle 128B (hidden behind nozzle 128 A) of pressure sensor 128, as illustrated in Figure 3G. Tn some embodiments, pressure sensor 128 may be a differential pressure sensor that measures and compares pressure readings from two points. In some embodiments, the pressure readings may be transmitted to an external input device (such as a microcontroller). In some embodiments, pressure readings obtained from two different ends 352 and 354 may be transmitted from the pressure sensor to a compute block within circuit board 1 12 or external to circuit board 1 12 to compute a flow velocity. In other embodiments, pressure sensor 128 is an absolute pressure sensor having two input nozzles 128A and 128B. A flow velocity measurement maybe computed from pressure readings obtained from two different openings 106A and 122A and input nozzles 128 A and 128B.

[0088] Tn another embodiment, sensor tube 1 10C (shown in Figure 3E) is further coupled with an additional sensor tube, such as sensor tube 110E, as illustrated in Figure 3H. In the illustrative embodiment, sensor tube 110E is coupled between sensor tube 110C and pressure sensor 114. Sensor tube 110E provides an additional pathway for gas 351 that enters opening 122A to flow to an additional pressure sensor, such as pressure sensor 114. In the illustrative embodiment, gas 351 that enters opening 122 A can simultaneously flow to pressure sensors 1 14 and 128. Since sensor tube 110E has a longer path length compared to sensor tube 1 IOC, simultaneous pressure measurements by pressure sensors 114 and 128 can provide a means to understand differences in pressure, if any, at a single measurement location, such as at the end 352 of opening 122A. Such a measurement can provide sensitivity of pressure measurement to length of sensor tubes and may be used to calibrate pressure sensors 114 and 128. [0089] Apparatus 350 described in association with Figures 3E-3H provide a way to dynamically measure pressure and compute flow velocity within the tube 302. Referring again to Figure 3C, a plurality of sensor tubes may be coupled between a respective pressure sensor and a respective opening in a plurality of openings distributed along a length of collector elements 104 and 120 (not visible). In some such embodiments, a pair of measurement locations corresponding to an opening on each corresponding collector element 104 and 120 may be chosen to provide a measurement of velocity that is parallel to the longitudinal axis (z-direction). A collection of pairs measurement locations along an entire length of collector element 104 and 1 0 can be used to obtain a pressure profile measurement. A velocity profile measurement across tube 302 can be computed from the pressure profile measurement. In the illustrative embodiment, collector 104 is positioned along a diameter of tube 302 to provide a maximum measurement range within tube 302.

[0090] While the tool and exhaust are located at opposite ends of each other as shown in Figures 3E-3H, the orientation of the tool and exhaust relative to collector elements 104 and 120 can be reversed. In a reversed configuration, gas 351 will be directed in a negative z-direction. Referring again to Figure 3E, in some such embodiments, tubes 110A and 110C can be inserted into ends 354 and 352, respectively to measure gas 351 flowing in an opposite direction (-z direction).

[0091] Figure 31 is a flowchart of method 360 of measuring one or more gas flow properties in tube 302 (Figure 3B) by using an exhaust monitoring apparatus 101. In an embodiment, tube 302 may be an exhaust pipe. Method 360 begins at operation 361 by intaking a gas through a first opening in a first collector element and a second opening in a second collector element of the exhaust monitoring apparatus. The first collector element and a second collector element are separated by a distance within the exhaust pipe. Method 360 continues at operation 362, by transporting the gas from both the first opening and the second opening to one or more pressures sensors located within the exhaust pipe. Method 360 continues at operation 363 by utilizing a first sensor tube to transport the gas from the first opening to the one or more pressure sensors and measure a first pressure within the first sensor tube. Operation 364 continues by utilizing a second sensor tube to transport the gas from the second opening to the one or more pressure sensors and measure a second pressure within the second sensor tube. The method 360 concludes at operation 365 by outputting a pressure reading at least partially based on the first pressure and the second pressure measured by the one or more pressure sensors. In some embodiments, method 360 docs not conclude at 365, one or more additional calculation may be performed based on the obtained pressure reading. While not shown in Figure 31, in some embodiments, other sensors may be coupled to the first and second sensor tubes to obtain other gas flow properties such as temperature.

[0092] In some embodiments, the method 360 further includes computing a flow velocity based on the first pressure, the second pressure, and a predetermined value of a density of the gas. In some embodiments, one or more operations of method 360 may be skipped, rearranged, or omitted. While the examples here are primarily directed to exhaust monitoring, this does not preclude the in-line gas flow monitoring system or the exhaust monitoring apparatus to be used in other applications. [0093] Figure 4A illustrates a simplified cross-sectional illustration of an inline gas monitoring apparatus 400 including exhaust monitoring apparatus 101, and damper 402 coupled with tube 302. Sensor tubes and pressure sensors are removed for clarity. As shown, damper 402 may be implemented to control a total volume and flow of gas 408 within tube 302. In some embodiments, damper 402 includes a rotor 404 and blade 406 coupled with rotor 404. As shown, rotor 404 extends along a center line (in the x-direction) of blade 406 and along a diameter of tube 302. In some embodiments, rotor 404 may extend parallel to the collector element 120 or 104. In some embodiments, rotor 404 can execute a complete 360 degrees rotation (denoted by angle theta) about an axis of the blade 406. A 360 degree rotation can enable fine control of gas flow through tube 302. In some embodiments, rotor 404 and blade 406 have a thickness, TB, that is less than a lateral thickness, T4, of either collector element 104 or 120. Hence, when a surface 406A of blade 406 is oriented parallel to inner sidewall 302A of tube 302, the damper will have little to no impact on gas flow within tube 302. In some embodiments, blade 406 may have a circular plane surface area (orthogonal to a longitudinal or z-axis of tube 302 in the Figure) to effectively provide damping. In some such embodiments, rotor 404 may extend along a diameter of tube 302, but necessarily parallel to collector element 120 or 104. When blade 406 is circular, blade 406 can have a diameter DRO, that is less than diameter, DT, of tube 302. In some embodiments, DRO is between 5%-25% smaller than DT. In other embodiments, DRO, is substantially equal to DT for maximum damping. In some embodiments, damper 402 is a fan that rotates along the Y-axis and controls airflow along the Z-axis within tube 302.

[0094] In some embodiments, damper 402 is vertically separated from the collector element 120 by a separation distance SDC- Tn the illustrative embodiment, SDC represents a distance between rotor 404 and collector element 120. Separation SDC provides a safe operating distance where damper 402 docs not come into contact with exhaust monitoring apparatus 101. The separation is at least greater than one half the diameter, DRO. In some embodiments, SDC is between 3 cm and 30 cm.

[0095] Tn some embodiments, damper 402 is controlled by a controller external to the inline gas monitoring apparatus 400. In some embodiments, damper 402 may be controlled by circuit board 112 of the exhaust monitoring apparatus 101.

[0096] Damper 402 may be implemented within a substrate processing system 410, as illustrated in Figure 4B. In some embodiments, substrate processing system 410 includes one or more components of substrate processing system 100 (illustrated in Figure 1A). Tn the illustrative embodiment, the exhaust lines 107A-107F each include a damper, such as for example, dampers 402A, 402B, 402C, 402D, 402E and 402F (402A-402F). In an embodiment, pressure is monitored in each of exhaust lines 107A-107F by an exhaust monitoring apparatus 101 within each respective exhaust line 107A-107F. Flow velocity of gases within exhaust lines 107A-107F can be computed by a method outlined above. Flow velocity may be dynamically computed from dynamic measurements of pressure. Flow velocities within each exhaust lines 107A-107F can be compared to each other. If required, flow velocities in one or more of the exhaust lines 107A-107F may be altered by rotating a respective damper 402A-402F. Rotation of a respective damper 402A-402F can, for example, increase or decrease gas flow velocity within a respective exhaust line 107A-107F. In some embodiments, the increase or decrease of gas flow can be up to a maximum or a minimum level that is determined by a respective exhaust fan coupled with exhaust lines 107A-107F and a rotation angle of the damper. As such, any of the dampers 402A-402F may be dynamically adjusted to a desired set point within each exhaust line 107A-107F.

[0097] While embodiments of the present disclosure are described in the context of gas monitoring in an exhaust pipe, the application of the exhaust monitoring apparatus described in the present disclosure is not limited to such use. In some embodiments, one or more embodiments of the exhaust monitoring apparatus may be used in other gas flow pipes or tubes within a semiconductor fabrication equipment. In some embodiments, one or more embodiments of the exhaust monitoring apparatus may be used in other gas flow pipes throughout a fabrication plant. In some embodiments, the exhaust monitoring apparatus is light weight and configured to communicate with other monitoring devices within a fabrication plant.

[0098] Figure 5 illustrates a block diagram of controller system 500 located on circuit board 112 according to some embodiments of the present disclosure. Controller system 500 includes input controller 501, power block 502, microcontroller block 503, sensor block 504, and output controller 505. Circuit board 112 illustrated in Figure IB may include input controller 501 and output controller 505. In some embodiments, input controller 501 includes an interface to receive input signals. Input signals may be received by any suitable interface such as Universal Serial Bus (USB) compliant interface, I2C, Thunderbolt, serial interface, parallel interface, etc. In some embodiments, input controller 501 instructs power block 502 to provides a certain amount of power to the various blocks of controller system 500. In other embodiments, input controller 501 can be used to download one or more programs to microcontroller block 503. In some embodiments, microcontroller block 503 includes or is coupled to a wireless circuitry (not shown). The wireless circuitry may allow microcontroller block 503 to communicate with other devices such as a server, another wireless device, etc. As such, pressure readings and/or calculations may be retrieved wirelessly from microcontroller block 503. In some embodiments, pressure sensors 1 14, and 128 can be calibrated by microcontroller block 503. Instructions for calibrating pressure sensors 114, and 128 can be received wirelessly or by wired means, in accordance with some embodiments.

[0099] In some embodiments, power block 502 includes a DC-DC converter, a linear converter (e.g., low dropout regulator), or any other suitable voltage regulator. In some embodiments, power block 502 can provide different power levels to different blocks according to their specifications. In some embodiments, power block includes a rechargeable battery or backup battery to operate controller system 500 in the absence of input power. In some embodiments, microcontroller block 503 includes any suitable processor and/or associated components to process the readings by sensor block 504.

[00100] In some embodiments, microcontroller block 503 includes a processor system described with reference to Figure 6. Referring to Figure 5, in some embodiments, sensor block 504 includes one or more sensors. In some embodiments, the one or more sensors include an absolute pressure sensor and/or a differential pressure sensor. In some embodiments, the one or more sensors include a temperature sensor. The readings from the one or more sensors are provided to microcontroller block 503 for processing. The readings are then transmitted via output controller 505 to another device. In other embodiments, microcontroller block 503 can be programmed to perform measurements such as comparing pressure readings from different pressure sensors (such as pressure sensors 1 14 and 128 in Figure 3E) and computing a flow velocity. Microcontroller block 503 can then transmit flow velocity information to output controller 505. In some embodiments, microcontroller block 503 is configured to adjust sensitivity of the one or more sensors. In some embodiments, output controller 505 includes wired and/or wireless means to communicate with an external device. In some embodiments, various components of controller system 500 can be recharacterized in one or more blocks. [00101] Figure 6 illustrates a processor system 600 with machine readable storage media having instructions that when executed cause a microcontroller (e.g., microcontroller block 503 in Figure 5) in a circuit board of an exhaust monitoring apparatus 101 to measure and report gas properties, in accordance with some embodiments. Processes described in various embodiments of the present disclosure may be stored in a machine-readable medium (e.g., 603) as computer- executable instructions. In some embodiments, processor system 600 comprises memory 601, processor 602, machine-readable storage media 603 (also referred to as tangible machine- readable medium), communication interface 604 (e.g., wireless or wired interface), and network bus 605 coupled together as shown. In some embodiments, the various components of system 600 may be part of microcontroller block 503.

[00102] In some embodiments, processor 602 is a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a general-purpose Central Processing Unit (CPU), or a low power logic implementing a simple finite state machine to perform various processes described herein.

[00103] In some embodiments, the various logic blocks of processor system 600 are coupled together via network bus 605. Any suitable protocol may be used to implement network bus 605. In some embodiments, machine-readable storage medium 603 includes instructions (also referred to as the program software code/instructions) for measuring gas pressure and gas flow and/or controlling a damper within a measurement apparatus, as described above with reference to various embodiments.

[00104] In one example, machine-readable storage media 603 is a machine-readable storage media with instructions for measuring gas pressure and gas flow (herein machine-readable medium 603) and for reporting the measured gas pressure. Machine-readable medium 603 has machine-readable instructions, that when executed, cause processor 602 to perform the method of measuring and/or reporting as discussed with reference to various embodiments.

[00105] Program software code/instructions associated with various embodiments may be implemented as part of an operating system or a specific application, component, program, object, module, routine, or other sequence of instructions or organization of sequences of instructions referred to as "program software code/instructions," "operating system program software code/instructions," "application program software code/instructions," or simply "software" or firmware embedded in processor. In some embodiments, the program software code/instructions associated with processes of various embodiments are executed by processor system 600. [00106] In some embodiments, machine-readable storage media 603 is a computer executable storage medium 603. In some such embodiments, the program software code/instructions associated with various embodiments are stored in computer executable storage medium 603 and executed by processor 602. Here, computer executable storage medium 603 is a tangible machine-readable medium 603 that can be used to store program software code/instructions and data that, when executed by a computing device, causes one or more processors (e.g., processor 602) to perform a process.

[00107] The tangible machine-readable medium 603 may include storage of the executable software program code/instructions and data in various tangible locations, including for example ROM, volatile RAM, non-volatile memory and/or cache and/or other tangible memory as referenced in the present application. Portions of this program software code/instructions and/or data may be stored in any one of these storage and memory devices. In some embodiments, the program software code/instructions can be obtained from other storage, including, e.g., through centralized servers or peer to peer networks and the like, including the Internet. Different portions of the software program code/instructions and data can be obtained at different times and in different communication sessions or in the same communication session.

[00108] The software program code/instructions associated with the various embodiments can be obtained in their entirety prior to the execution of a respective software program or application. Alternatively, portions of the software program code/instructions and data can be obtained dynamically, e.g., just in time, when needed for execution. Alternatively, some combination of these ways of obtaining the software program code/instructions and data may occur, e.g., for different applications, components, programs, objects, modules, routines or other sequences of instructions or organization of sequences of instructions, by way of example. Thus, it is not required that the data and instructions be on a tangible machine-readable medium 603 in entirety at a particular instance of time.

[00109] Examples of tangible machine-readable medium 603 include but are not limited to recordable and non-recordable type media such as volatile and non-volatile memory devices, read only memory (ROM), random access memory (RAM), flash memory devices, floppy and other removable disks, magnetic storage media, optical storage media (e.g., Compact Disk Read- Only Memory (CD ROMS), Digital Versatile Disks (DVDs), etc.), among others. The software program code/instructions may be temporarily stored in digital tangible communication links while implementing electrical, optical, acoustical, or other forms of propagating signals, such as carrier waves, infrared signals, digital signals, etc. through such tangible communication links. [00110] Besides what is described herein, various modifications may be made to the disclosed embodiments and implementations thereof without departing from their scope. Therefore, illustrations of embodiments herein should be construed as examples only, and not restrictive to the scope of the present disclosure. The scope of the invention should be measured solely by reference to the claims that follow.

Claims

CLAIMS What is claimed is:

1. A gas flow monitoring system comprising: a tube; a peripheral support frame coupled inside the tube, wherein the peripheral support frame comprises one or more collector elements extending laterally across the peripheral support frame, wherein the one or more collector elements comprise a plurality of openings configured to intake gas; and a circuit board coupled with the peripheral support frame inside the tube, the circuit board comprising: one or more pressure sensors coupled to the one or more collector elements; and a transmitter circuitry to transmit readings from the one or more pressure sensors.

2. The gas flow monitoring system of claim 1, wherein the tube comprises a circular cross section.

3. The gas flow monitoring system of claim 1, wherein the one or more collector elements comprises a collector clement, wherein the collector clement spans across the tube, and wherein one or more openings in the collector element are configured to intake exhaust gases flowing within the tube.

4. The gas flow monitoring system of claim 1, wherein an individual pressure sensor of the one or more pressure sensors comprises one or more nozzles.

5. The gas flow monitoring system of claim 1, wherein at least one pressure sensor is an absolute pressure sensor.

6. The gas flow monitoring system of claim 1, wherein at least one pressure sensor is a differential pressure sensor.

7. The gas flow monitoring system of claim 1 , wherein the one or more collector elements comprise a first plurality of openings along a first direction parallel to a longitudinal axis of the tube, and a second plurality of openings along the first direction.

8. The gas flow monitoring system of claim 7 further comprising one or more sensor tubes coupled between a respective opening within the one or more collector elements and a respective nozzle of the one or more pressure sensors.

9. The gas flow monitoring system of claim 1, wherein the one or more collector elements comprise: a first collector element along a first position of the peripheral support frame; and

22 a second collector element separated from the first collector element, wherein the first collector element and the second collector element are separated along a longitudinal axis of the tube. 0. The gas flow monitoring system of claim 9, wherein a separation distance between the first collector element and the second collector element is between 5 cm and 100 cm. 1 . The gas flow monitoring system of claim 9, wherein the first collector element and the second collector clement comprise: a first plurality of openings along a second direction parallel to the longitudinal axis of the tube; and a second plurality of openings along a third direction orthogonal to a longitudinal axis of the tube. 2. The gas flow monitoring system of claim 11 further comprising: a first plurality of sensor tubes, wherein individual ones of the first plurality of sensor tubes are coupled between a respective opening within the first collector element and a respective nozzle of the one or more pressure sensors; and a second plurality of sensor tubes, wherein individual ones of the second plurality of sensor tubes are coupled between a respective opening within the second collector element and a respective nozzle of a remaining one or more pressure sensors not coupled with the first plurality of sensor tubes. 3. The gas flow monitoring system of claim 1, wherein the tube further comprises an opening adjacent to the peripheral support frame, the opening configured to measure pressure within the tube relative to a pressure external to the tube. 4. The gas flow monitoring system of claim 1, further comprising a damper within the tube, wherein the damper is longitudinally distant from the one or more collector elements, the damper comprising: a plate having a cross sectional area that is less than a cross sectional area of an opening of the tube; and a motor coupled with the plate, the motor configured to provide rotation of the plate about a line orthogonal a longitudinal axis. 5. The gas flow monitoring system of claim 1, wherein the circuit board is coupled to a peripheral portion of the peripheral support frame. 6. An exhaust monitoring apparatus comprising: a peripheral support frame comprising one or more collector elements, the one or more collector elements extending laterally across the peripheral support frame, wherein the one or more collector elements comprise a plurality of openings configured to intake gas; and a circuit board coupled with the peripheral support frame, the circuit board comprising: a plurality of pressure sensors coupled to the one or more collector elements; and a transmitter circuitry to transmit readings from the plurality of pressure sensors. The exhaust monitoring apparatus of claim 16, wherein the peripheral support frame comprises a circular ring structure, wherein the one or more collector elements comprises a collector clement that extends across a diameter of the circular ring structure. The exhaust monitoring apparatus of claim 17, wherein the peripheral support frame further comprises a pair of vertical support columns on opposite ends of the diameter of the circular ring structure, the pair of vertical support columns extending away from the circular ring structure, wherein the collector element is a first collector clement, and the one or more collector elements further comprises a second collector element, wherein the second collector element is coupled with each of the pair of vertical support columns. The exhaust monitoring apparatus of claim 18, wherein the first collector element is directly above and parallel to the second collector clement. The exhaust monitoring apparatus of claim 19, wherein the first collector element comprises a first one or more openings and the second collector element comprises a second one or more openings. The exhaust monitoring apparatus of claim 20, wherein individual ones of the first collector element and the second collector element comprise a first plurality of openings along a direction parallel to a longitudinal axis of a peripheral support structure, and a second plurality of openings along a direction orthogonal to the longitudinal axis of the peripheral support frame. The exhaust monitoring apparatus of claim 17, wherein the circuit board is coupled with the circular ring structure. A method for determining one or more gas flow properties in an exhaust pipe using an exhaust monitoring apparatus, the method comprising: intaking a gas through a first opening in a first collector element and a second opening in a second collector element of the exhaust monitoring apparatus, wherein the first collector element and a second collector clement arc separated by a distance within the exhaust pipe; transporting the gas from both the first opening and the second opening to one or more pressure sensors located within the exhaust pipe, wherein a first sensor tube is used to transport the gas from the first opening to the one or more pressure sensors, and a second sensor tube is used to transport the gas from the second opening to the one or more pressure sensors; measuring, by the one or more pressure sensors, a first pressure within the first sensor tube: measuring, by the one or more pressure sensors, a second pressure within the second sensor tube; and outputting a pressure reading at least partially based on the first pressure and the second pressure measured by the one or more pressure sensors. The method of claim 23 further comprising computing a flow velocity based on the first pressure, the second pressure, and a predetermined value of a density of the gas. The method of claim 23, wherein the first opening is a first plurality of openings, wherein the second opening is a second plurality of openings, wherein intaking gas further comprises intaking gas through the first plurality of openings and the second plurality of openings. The method of claim 23, wherein the first sensor tube is coupled with an opening at a first center of the first collector element, wherein the second sensor tube is coupled with an opening at a second center of the second collector element, wherein the first center is separated from the second center along a direction parallel to a longitudinal axis of the exhaust monitoring apparatus, and wherein measuring the first pressure and the second pressure comprises measuring along the longitudinal axis. The method of claim 23, wherein the first pressure is measured at a first location that is not at a center of the first collector, wherein the second pressure is measured at a second location that is not at a center of the second collector, and wherein a direction between the first location and the second locations is parallel to a longitudinal axis of the exhaust monitoring apparatus. The method of claim 25, wherein the first plurality of openings is along a first diameter of the exhaust monitoring apparatus, wherein the second plurality of openings is along a second diameter of the exhaust monitoring apparatus, wherein the method further comprises simultaneously measuring pressure along the first plurality of openings and along the second plurality of openings.

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