Exhaust gas monitoring for photoresist adhesion control.

Abstract

An exhaust flow monitoring system (100) for a photolithography track of an IC manufacturing process includes a reaction chamber (102) including a housing (104), an inflow port (106), and an outflow port (112), the housing (104) including a heat plate (108) for heating a semiconductor process wafer (110) for a predetermined time. An inflow pipe (117) coupled to the inflow port (106) supplies a photoresist adhesion promoter (119) in gas form to the reaction chamber (102). An outflow pipe (130) coupled to the outflow port (112) is operable to remove by-products from the reaction chamber (102) as an exhaust flow. At least one gas sensor manifold assembly (132) is coupled to the outflow pipe (130) for monitoring an exhaust flow from the reaction chamber (102) to detect the presence of one or more by-products of a reaction between the photoresist adhesion promoter (119) and the semiconductor process wafer (110).

Description

[Technical field]

[0001] The described implementations relate generally to the field of semiconductor manufacturing and more specifically, but not exclusively, to exhaust gas monitoring to facilitate photoresist adhesion control. [Background technology]

[0002] Semiconductor circuits are manufactured by using a sequence of semiconductor substrate preparation, patterning, etching, metallization, etc., which can be used in various combinations to form the desired semiconductor or integrated circuit in the substrate. As part of the semiconductor manufacturing process, photolithography is used to define patterns representing specific devices or circuit structures on the surface of a semiconductor wafer. This pattern is created with photoresist, which protects the underlying substrate from subsequent processing. The physical or electrical properties of the unprotected surface are altered by a number of subsequent processing steps, such as etching, deposition, ion implantation, sputtering, etc. The above-described cycle of patterning and subsequent processing may be repeated several times until the entire device is completed.

[0003] Good adhesion of photoresist is important to ensure the integrity of pattern transfer during photolithography. To prepare semiconductor process wafers for better adhesion of photoresist, a priming process using a suitable adhesion promoter is often performed. Any failure that compromises the integrity of the priming process can be costly, since the resulting poor adhesion of photoresist can cause device defects (e.g., due to failure in the subsequent etching step), which may not be detected until after many processing steps have been performed. Summary of the Invention

[0004] In one aspect, a system implementation is described for monitoring exhaust gases of an adhesion promotion reaction process to determine whether the reaction process is performed in a satisfactory manner. The apparatus includes, among other things, a reaction chamber including a housing, an inflow port, and an outflow port, the housing including a heat plate for heating a semiconductor process wafer at a predetermined temperature for a predetermined amount of time. An inlet or inflow pipe is coupled to the inflow port to supply a photoresist adhesion promoter in gas form to the reaction chamber (e.g., hexamethyldisilazane (HMDS) vapor phase in a carrier gas). An outlet pipe is coupled to the outflow port to exhaust by-products from the reaction chamber. At least one gas sensor manifold assembly is provided coupled to the outlet pipe to monitor the exhaust flow from the reaction chamber to detect the presence of one or more by-products of the reaction between the photoresist adhesion promoter and the semiconductor wafer.

[0005] In another aspect, one implementation of a method for manufacturing an integrated circuit (IC) is described. The method includes, among other things, applying an adhesion promoter in gas form to a semiconductor process wafer disposed in a reaction chamber prior to applying a photoresist (PR) layer in a photolithography step used in manufacturing an IC on the semiconductor process wafer, and monitoring an exhaust stream flowing from the reaction chamber to detect the presence of one or more by-products of a reaction between the adhesion promoter and the semiconductor process wafer. In response to determining that the detected by-products are present in the exhaust stream in an amount above a corresponding threshold, the semiconductor process wafer may proceed to a next stage in IC manufacturing. In one variation, an example process flow may include, but is not limited to, performing at least one of: (i) terminating further processing of the semiconductor process wafer (e.g., the semiconductor process wafer does not proceed to PR application), and / or (ii) designating the semiconductor process wafer for rework or scrap. [Brief description of the drawings]

[0006] One implementation of the present description is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings. Different references to "an" or "one" implementation in this description are not necessarily to the same implementation, and such references may mean at least one. Furthermore, when a particular feature, structure, or characteristic is described in connection with one implementation, it is believed to be within the knowledge of one skilled in the art to implement such feature, structure, or characteristic in connection with other implementations, whether or not explicitly described.

[0007] The accompanying drawings, which are incorporated in and form a part of this specification, illustrate one or more example implementations of the present disclosure. Various advantages and features will become apparent from the following detailed description, taken in conjunction with the appended claims, and with reference to the accompanying drawings.

[0008] [Figure 1] 1 illustrates an exemplary system including an exhaust gas monitoring device for use in a photolithography track of an IC manufacturing process, according to one implementation.

[0009] [Figure 2A] 1 illustrates an example arrangement of multiple gas sensor manifold assemblies that may be deployed to monitor exhaust gas by-products, according to one implementation. [Figure 2B] 1 illustrates an example arrangement of multiple gas sensor manifold assemblies that may be deployed to monitor exhaust gas by-products, according to one implementation.

[0010] [Diagram 3] 1 illustrates various components of a gas sensor manifold assembly that may be deployed to monitor trimethylamine by-product in an exhaust stream according to one implementation.

[0011] [Figure 4] 1A-1D show various views of a housing block and cover plate of a trimethylamine sensor manifold assembly according to one implementation. [Diagram 5]1A-1D show various views of a housing block and cover plate of a trimethylamine sensor manifold assembly according to one implementation.

[0012] [Figure 6] 1A-1D show various views of an assembled trimethylamine sensor manofold assembly according to one implementation.

[0013] [Figure 7] 1 illustrates various components of a gas sensor manifold assembly that may be deployed to monitor ammonia by-product in an exhaust stream, according to one implementation.

[0014] [Figure 8] 1A-1D show various views of a housing block and cover plate of an ammonia sensor manifold assembly according to one implementation. [Figure 9] 1A-1D show various views of a housing block and cover plate of an ammonia sensor manifold assembly according to one implementation.

[0015] [Figure 10] 1A-1D show various views of an assembled ammonia sensor manifold assembly according to one implementation.

[0016] [Figure 11] 1 illustrates an example seal arrangement for a trimethylamine sensor manifold assembly according to one implementation.

[0017] [Figure 12] 1 illustrates an example seal arrangement for an ammonia sensor manifold assembly according to one implementation.

[0018] [Figure 13A] 1 illustrates an example method according to one implementation. [Figure 13B] 1 illustrates an example method according to one implementation. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] The embodiments are described with reference to the accompanying drawings, in which like reference numerals are generally used to refer to like elements. The figures are not drawn to scale and are provided merely to illustrate examples. Numerous specific details, relationships, and methods are described below to provide an understanding of one or more examples. However, some embodiments may be practiced without such specific details. In other examples, well-known circuits, subsystems, components, structures, and techniques are not shown in detail so as not to obscure an understanding of the embodiments. Thus, the described embodiments may be practiced without such specific components.

[0020] In the following description, reference may be made to the accompanying drawings, and certain directional terms, such as, for example, "upper", "lower", "top", "bottom", "left", "right", "front", "back", "vertical", "horizontal", etc., may be used with respect to the orientation of the figures or their illustrated elements being described. Because components of some embodiments can be arranged in a number of different orientations, the directional terms are used for purposes of explanation and are in no way limiting. Similarly, references to features referred to as "first", "second", etc. do not indicate any particular order, importance, etc., and such references may be interchanged, mutatis mutandis, depending on the context, implementation, etc. Additionally, features of the examples described herein may be combined with each other, unless otherwise noted.

[0021] As used herein, the term "couple" means either an indirect or direct conductive connection, unless qualified as "communicatively coupled," which may include a wireless connection. Thus, when a first device couples to a second device, the connection may be through a direct conductive connection or through an indirect conductive connection via other devices and connections.

[0022] 1, an exemplary apparatus 100 for use in a photolithography track of an integrated circuit (IC) manufacturing process is shown, where, according to one implementation, an exhaust monitoring device 103 may be provided. As described further below, the system 100 may be applied to any IC manufacturing flow where an adhesion promoter (AP) material is applied to a semiconductor process wafer prior to a photoresist (PR) step to improve photoresist adhesion at any process stage requiring photolithographic patterning (e.g., during either the front-end-of-line (FEOL) or back-end-of-line (BEOL) stages before a final passivation layer is added to the wafer).

[0023] Without being limiting, an exemplary system 100 and associated exhaust monitoring device 103 are described according to one implementation in which a gaseous photoresist adhesion promoter, such as, for example, hexamethyldisilazane (HMDS), which belongs to a class of hexaalkyldisilazane promoters, is applied to a semiconductor process wafer, including a silicon substrate, in a reaction chamber to promote a reaction process that primes the surface to enhance adhesion of a subsequent PR layer. Depending on the substrate material and associated process layers thereon, the HMDS reaction process may be performed to release specific by-products indicative of reliable PR adhesion-promoting surface chemistry, and one or more specific by-products (also referred to as benchmark by-products) may be monitored to determine whether the reaction process for performing HMDS treatment of the process wafer has performed satisfactorily or otherwise (e.g., impaired in some way).

[0024] In one arrangement, the system 100 includes a reaction chamber 102 including a housing 104, one or more inflow ports 106, and one or more outflow ports 112, where a thermal plate 108 may be disposed within the interior 105 of the housing 104, which is equipped and instrumented to subject at least one semiconductor process wafer 110 to a set of process conditions, e.g., predetermined temperatures, vacuum pressures, timing ranges, etc., which may depend, among other things, on the composition of the semiconductor wafer substrate, the particular photolithography layer, the type and chemistry of photoresist used, etc. For purposes herein, the semiconductor process wafer 110 may also be referred to, without loss of generality, as a semiconductor wafer, a process wafer, a work-in-process (WIP) wafer, etc., which may be included in a suitable holder, tray, carrier, or wafer conveyor (not specifically shown in FIG. 1 ), and the process wafer 100 may be disposed horizontally, vertically, or in other orientations when disposed within the housing 104 for processing. Depending on the implementation, the reaction chamber 102 may be configured to provide both vacuum baking and vapor priming, which may be used to generate a heated vacuum environment within the interior 105 for dehydration and vapor priming of semiconductor process wafers in a single cycle. Thus, the reaction chamber 102 may also be referred to generally synonymously by a variety of informal and formal terms in some arrangements, such as a "bake oven," "vapor chamber," or other similar terms.

[0025] In one arrangement, a gas (e.g., nitrogen) may be used as a carrier to transport HMDS in gaseous form through one or more piping or conduit systems associated with the reaction chamber 102. Illustratively, a nitrogen gas supply canister 120 is operable to supply N2 gas to a tank or container 118 containing liquid HMDS 123 through a conduit section 121 that may be monitored by an N2 sensor 122. In one arrangement, the HMDS container 118 may be pressurized with N2 gas. Depending on the implementation, the N2 gas may be flowed over or bubbled through the surface of the liquid HMDS 123 during processing, creating an HMDS-rich gas phase or aerosol mixture 119, which is piped to the reaction chamber 102 via conduit sections 116, 117. A flow meter 124 and a vacuum sensor 126 may be coupled to the conduit portions 116, 117 at locations suitable for monitoring flow conditions of the HMDS vapor and N2 gas mixture 119, and at least the conduit portion 117 may be deployed as an inlet pipe coupled to the inflow port 106 of the housing 104.

[0026] In one arrangement, the housing 104 of the reaction chamber 102 may include one or more perforated applicators 114 (informally referred to as "showerheads") coupled to or otherwise associated with in-flow ports 106 for uniformly distributing the adhesion promoter mixture as a flow 125 over a semiconductor process wafer 110 disposed within the housing 104, thereby facilitating a substantially uniform diffusion of the gaseous adhesion promoter material over the wafer surface. Under appropriate process conditions, one or more chemical and / or surface reactions, collectively referred to as reaction processes, involving HMDS and a number of reactants (e.g., including but not limited to surface HO, internal atmosphere HO, oxygen, various ceramic and oxide, metallic / non-metallic surface layers depending on topography, wafer substrate material, etc.) may be initiated within the reaction chamber 102 to effect proper surface treatment of the semiconductor wafer. HMDS as a silane coupling agent acts to react with metal and ceramic surfaces to form hydrophilic trimethylsilanol (TMSiOH) on the surfaces, which facilitates easier coverage of the semiconductor wafer surface with photoresist in a subsequent step. HMDS also acts to react with ambient moisture and gradually convert it to ammonia (NH3) and methylsilanol.

[0027] Thus, various by-products resulting from the above-described reaction process may include at least one of ammonia, trimethylamine, and one or more volatile organic compounds (VOCs), which may be removed as an exhaust stream from the reaction chamber 102 via one or more outlet pipes 130 coupled to the housing 104 at corresponding outflow ports 112. At least one gas sensor manifold assembly 132 including suitable gas sensors 138 (e.g., an ammonia sensor, a trimethylamine sensor, a VOC sensor, etc.) is coupled to the outlet pipes 130 as part of the exhaust monitoring device 103 to detect the presence of one or more benchmark by-products (depending on which by-products are selected for measurement) and facilitate determining whether the HMDS reaction process has performed satisfactorily or otherwise (e.g., due to a leak or defect resulting in a reduction or elimination of HMDS vapor being delivered into the reaction chamber 102). The electrical interface 134 of the sensor 138 may be coupled to a data acquisition (DAQ) unit 140 for collecting sensor data and transmitting the data to a host computer 142 using any known or previously unknown data collection / transmission protocol in conjunction with suitable wireless and / or wired communication technologies and infrastructure, where the data may be processed to generate appropriate reports, notifications / alarms, etc. regarding the status of the HMDS reaction process (generally referred to as "actionable process intelligence"). Depending on the implementation, the host computer 142 may be deployed as a local or remote host, or in a cloud-based data center associated with the IC manufacturing facility.

[0028] In one arrangement, process conditions for achieving an exemplary HMDS reaction process in the reaction chamber 102 may include heating the semiconductor wafer 110 disposed in the housing 104 at a temperature ranging from about 70° C. to 150° C. for about several to several tens of seconds (e.g., 5 to 30 seconds) at an internal ambient pressure of about 1 Torr. Depending on the particular IC manufacturing flow, the exemplary HMDS process stage may include other steps, procedures, or operations in several additional and / or alternative arrangements. For example, a purge cycle may be used to purge ambient gas from the interior 105 of the reaction chamber 102 before delivering HMDS. In a pump and purge arrangement, a series of vacuum and nitrogen applications may be provided to remove ambient oxygen and moisture from the interior 105. Pre-heated nitrogen may be delivered to heat the semiconductor wafer to a desired process temperature. In some arrangements, the reaction chamber 102 may be evacuated to a low pressure and refilled with pure nitrogen several times to substantially completely remove ambient moisture. Prior to delivering the HMDS and nitrogen mixture, the ambient pressure within the reaction chamber 102 may be pumped down to an appropriate pressure (e.g., about 1 Torr) depending on the tooling conditions. The HMDS and nitrogen mixture may be delivered in a diffusion manner for a specified amount of time to accomplish the HMDS reaction process as exemplified above. Excess HMDS and gaseous by-products may be exhausted as an exhaust stream, after which additional vacuum / nitrogen cycles may be used to ensure complete removal of the by-products from the reaction chamber 102.

[0029] Continuing to refer to FIG. 1, a gas sensor manifold assembly 132 may be coupled to the outlet pipe 130 at a suitable location before the exhaust stream is conveyed to an exhaust system associated with the reaction chamber tool (not specifically shown in FIG. 1) to safely remove gaseous by-products of the HMDS reaction process for proper environmental treatment. Depending on the implementation, an example system may include an active exhaust system (e.g., a pump-based mechanism) or a passive exhaust system (e.g., a passive ventilation system). In one arrangement, the gas sensor manifold assembly 132 may be axially disposed between the first portion 136A and the second portion 136B of the outlet pipe 130 such that a sensor 138 disposed within the manifold assembly 132 does not obstruct access to the gaseous exhaust stream flowing through the outlet pipe 131, as described in further detail below.

[0030] In some arrangements, the exhaust monitoring device 103 may include multiple gas sensor manifold assemblies that may be coupled to the outlet pipe 130 at various locations, and each gas sensor manifold assembly may be configured to include a sensor operable to detect and measure a particular by-product in the exhaust stream. As described above, such sensors may include one or more ammonia sensors, one or more trimethylamine sensors, one or more VOC sensors, etc., in any combination, and the electrical interface of each of the sensors may be coupled to one or more DAQ units. Figures 2A and 2B show example arrangements of multiple gas sensor manifold assemblies that may be deployed according to one implementation. The arrangement 200A of Figure 2A illustrates an arrangement scenario in which two or more gas sensor manifold assemblies 202-1, 202-2 including respective sensors 204-1, 204-2 are arranged in a serial configuration along the outlet pipe section 250 leading from the reaction chamber. The electrical interfaces 206-1, 206-2 of the sensors 204-1, 204-2 are each operable to be coupled to a separate DAQ or to a single DAQ operable to support multiple sensors collectively shown as DAQ 208. The arrangement 200B of FIG. 2B is an example of an arrangement scenario in which multiple gas sensor manifold assemblies 202-1, 202-2 are arranged in a parallel configuration along respective outlet pipe sections 262-1, 262-2 of an outlet pipe section 250 exiting from the reaction chamber. The outlet pipe section 250 is operable to branch into multiple parallel pipe sections, e.g., sections 262-1, 260-2, to achieve parallel exhaust stream flows, which may merge into a single pipe section before the exhaust stream is delivered to the exhaust system. Similar to the arrangement 200A of FIG. 2A, the electrical interfaces 206-1, 206-2 of each of the sensors 204-1, 204-2 may each be coupled to a separate DAQ or to a single DAQ operable to support multiple sensors.Example deployment scenarios may include any number of the configuration 200A of FIG. 2A, the configuration 200B of FIG. 2B, and / or any variations and combinations thereof, and the multiple gas sensor manifold assemblies 202-1, 202-2 may include sensors from the same or different types (e.g., any combination of ammonia sensors, trimethylamine sensors, and / or VOC sensors, etc.).

[0031] Generally, the exemplary gas sensor manifold assembly can be constructed from any suitable material (e.g., stainless steel) capable of withstanding the harsh chemical, physical, and other environmental conditions of an IC manufacturing line, particularly the tooling used in the PR adhesion promoter process. In one arrangement, the exemplary sensor manifold assembly can be deployed as a customizable mounting block configured to couple to an outlet pipe portion of a reaction chamber at any suitable location that allows the gas sensor to be safely placed in the path of the exhaust flow without leakage or the like. Thus, the described mounting block can be advantageously configured to provide robust protection of the gas sensor placed in its associated outlet pipe while ensuring the integrity of the vacuum system of the reaction chamber. Additionally, the customizable housing design of the mounting block is operable, for purposes herein, to facilitate the accommodation of any commercially available gas / vapor sensor and / or customized sensor in various deployment scenarios. In one arrangement, the exemplary gas sensor manifold assembly may be constructed and / or assembled as a single modular unit that may be installed in any style or type of reaction chamber equipment or tool system, and suitable inlet and outlet connections or ports may be provided in a mounting block for mounting the modular unit in axial alignment with an exhaust outlet pipe section. In one implementation, the exemplary gas sensor manifold assembly may include a mounting block (also referred to as a housing block) with suitable receptacles or spacing designed to accommodate the TGS2603 series trimethylamine sensor and the TGS826 ammonia sensor from Figaro USA Inc. and affiliates, although gas sensors from various sources may also be used according to some additional and / or alternative implementations.

[0032] Figure 3 illustrates various components of a trimethylamine sensor manifold assembly 300 that may be provided as a modular unit according to one implementation for deployment in the example exhaust gas monitoring device of Figure 1. In one arrangement, the assembly 300 includes a housing block 302A having a receptacle side 303 with a chamber or receptacle 304 contoured to receive a trimethylamine sensor 302D, where a cover plate 302B having an opening 310 for exposing the sensor 302D to external circuitry or wiring (e.g., for data acquisition) may be securely coupled to the housing block 302A using a variety of mechanical coupling mechanisms, such as screws, fasteners, bolts, etc. By way of example, the receptacle side 303 of the housing block 302A may be provided with a number of threaded holes 308 that are aligned with a number of corresponding threaded holes 309 in the cover plate 302B to facilitate a secure mechanical coupling. The sensor 302D may include a first body part 313 having a sensing portion 311A ​​and a second body part 315 having an electrical interface portion 311B. An O-ring seal 302C sized to seal the opening 310 in the cover plate 302B may be disposed around the second body part 315 of the sensor 302D, e.g., proximate to the electrical interface portion 311B of the sensor 302D, such that the O-ring seal 302C is compressed between the housing block 302A and the cover plate 302B when the housing block 302A is rigidly coupled to the cover plate 302B and the sensor 302D is positioned within a receptacle 304 with the electrical interface portion 311B exposed to external wiring / circuitry.

[0033] To provide coupling with the reaction chamber's stream outlet pipe and to facilitate the passage of the exhaust gas flow through the housing block 302A for sensing, a pair of orifices having a continuous hollow space therebetween may be provided in the housing block 302A, in which case a portion of the sensor receptacle 304 may be configured such that it opens into the hollow space (not specifically shown in FIG. 3), thereby allowing the sensing portion 311A ​​of the sensor 302D to protrude into the hollow space for contacting or immersing in the exhaust gas flow. By way of example, an opening 306 is shown in a first side 305 of the housing block 302A, as illustrated in the 3D view shown in FIG. A second opening (not shown in FIG. 3) may be provided on the second side 307 of the housing block 302A or on the same side as side 305, where a continuous hollow space (i.e., spatial continuity) may be accommodated (e.g., as a U-shape, horseshoe-shape, etc., with both openings on the same side of the housing block 302A) and the receptacle 304 may be contoured to have an opening that allows the sensing portion 311A ​​to access the exhaust gas flow without obstruction. In one arrangement, the incoming and outgoing pipe section may be coupled to one opening (e.g., referred to as an input opening) and the outgoing pipe section may be coupled to the other opening (e.g., referred to as an output opening) to pass the exhaust gas flow therebetween. In one arrangement, the input and output openings and the corresponding incoming and outgoing pipe sections may be threaded together with suitable sealing, although one skilled in the art will recognize that the mechanical coupling between each opening and the corresponding outgoing pipe section may be achieved in many variations.

[0034] 4 and 5 show various views of an example 3D representation of a housing block and cover plate of a trimethylamine sensor manifold assembly, such as assembly 300 of FIG. 3, illustrating additional details according to one implementation. FIG. 4 shows a front view 400A, a top view 400B, and a side view 400C of a housing block, generally designated by reference numeral 401, with openings 402, 404 interlocking with a cylindrical space 406 therebetween. A receptacle portion 408 of a receptacle 410 opens into and provides spatial continuity with the cylindrical space 406. A plurality of holes 412 are shown in the top view 400B of the housing block 401 to facilitate mechanical coupling with the cover plate as described above, and the holes 412 may be spaced apart from the sensor receptacle 410. FIG. 5 shows a top view 500A and a side view 500B of a cover plate 501 having a thickness 502. An opening 504 formed through the cover plate 501 can be sized and shaped to allow the electrical interface portion of the trimethylamine sensor access to external electronics while a sealing device such as, for example, an O-ring seal, gasket, or washer can be used to facilitate a tight seal and ensure vacuum integrity when mated with the receptacle 410 of the housing block 401. The cover plate 501 can be provided with a number of through holes 512 that align with corresponding holes 412 in the housing block 401, for example, as shown in top view 500A of the cover plate 501, to facilitate a tight mechanical coupling with the housing block 401 as described above.

[0035] 6 shows a front view 600A and a top view 600B of an assembled trimethylamine sensor manifold assembly 601 according to one implementation, with the housing block 401 and cover plate 501 assembled as a modular unit. The trimethylamine sensor 602 is disposed within the receptacle 410 such that the sensing portion 604 protrudes or otherwise extends into the hollow cylindrical space 406 extending between the openings 402 and 404, while the electrical interface portion 606 of the sensor 602 (shown without an associated electrical connector in this view) is exposed to facilitate an external electrical connection. Depending on whether an incoming or outgoing outlet pipe section is connected, either the openings 402, 404 can operate as an inflow or outflow port.

[0036] 11, therein is shown an example seal arrangement 1100, such as an O-ring seal, for the trimethylamine sensor manifold assembly of FIG. 3 according to one implementation. A trimethylamine sensor 1102 is shown with a sensing portion 1104 and an electrical interface portion 1106 (electrical connectors or pins not specifically shown). An O-ring seal 1108 is disposed around the sensor 1102 in close proximity to the electrical sensing portion 1106 to provide a tight seal in the modular manifold assembly, as described in detail above.

[0037] FIG. 7 illustrates various components of an ammonia sensor manifold assembly 700 that may be provided as a modular unit according to one implementation for deployment in the example exhaust gas monitoring device of FIG. 1. Similar to the trimethylamine sensor manifold assembly 300 of FIG. 3 above, the assembly 700 includes a housing block 702A having a receptacle side 703 with a chamber or receptacle 704 contoured to accommodate an ammonia sensor 702E, which may have a different form factor than a trimethylamine sensor. Due to the difference in sensor form factor, the sensor receptacle 704 of the housing block 702A may be of a different size, shape, and / or configuration than that of the housing block 302A. Also, sealing may require multiple sealing devices to ensure vacuum integrity given the different shape of the ammonia sensor. Apart from the differences discussed above, the ammonia sensor manifold assembly 700 may be configured as a single modular unit in a manner substantially similar to that of the trimethylamine sensor manifold assembly 300. Thus, the description given above with respect to FIG. 3 is generally applicable to FIG. 7, mutatis mutandis.

[0038] The ammonia sensor 702E may include a first body portion 713 having a sensing portion 711A and a second body portion 715 having an electrical interface portion 711B. The sensor receptacle 704 of the housing block 702A may be shaped such that a receptacle portion (not specifically shown in FIG. 7) may open into a hollow space extending between an input opening and an output opening, which may be located on two different sides or on the same side of the housing block 702A, for coupling with a respective outlet pipe portion. By way of example, only one opening 706 formed in the first side 705 is illustrated in the 3D representation of the housing block 702A. A plurality of holes 708 formed in the receptacle side 703 including the sensor receptacle 704 are aligned with a corresponding plurality of through holes 709 formed in the cover plate 700B to facilitate firm mechanical coupling with the ammonia sensor 702E after it is positioned in the receptacle 704, such that the sensing portion 711A extends into the hollow space formed in the housing block 702A and the electrical interface portion 711B is exposed to the outside world through the opening 710 in the cover plate 700B to facilitate electrical connection with the DAQ and associated circuit elements.

[0039] In one arrangement, to ensure vacuum integrity of the tooling system, a dual seal arrangement may be provided in which a first O-ring seal 702C is disposed around the first body portion 713 of the sensor 702E to seal the receptacle portion opening to the hollow space, and a second O-ring seal 702D is disposed around the second body portion 715, adjacent the electrical interface portion 711B, to seal the mechanical interface involving the second body portion 715 and opening 710 of the cover plate 700B.

[0040] 8 and 9 show various views of an example 3D representation of a housing block and cover plate of an ammonia sensor manifold assembly, such as assembly 700 of FIG. 7, illustrating additional details according to one implementation. FIG. 8 shows a front view 800A, a top view 800B, and a side view 800C of a housing block, generally designated by reference numeral 801, in which openings 802, 804 are connected with a cylindrical space 806 therebetween. A receptacle portion 808 of a receptacle 810 opens into and provides spatial continuity with the cylindrical space 806. A plurality of holes 812 are shown in the top view 800B of the housing block 801 to facilitate mechanical coupling with the cover plate as described above. FIG. 9 shows a top view 900A and a side view 900B of a cover plate 901 having a thickness 902. The opening 904 formed in the cover plate 901 can be sized and shaped to allow the electrical interface portion of the ammonia sensor access to external electronics while facilitating a tight seal with the receptacle 810 of the housing block 801 when mated therewith and a sealing device such as, for example, an O-ring seal, gasket, or washer can be used to ensure vacuum integrity. The receptacle 810 can also be contoured proximate to the receptacle portion 808 such that another sealing device (e.g., selected from an O-ring seal, gasket, washer, etc.) can be positioned to provide a tight seal between the receptacle portion 808 and the sensing portion of the sensor. As mentioned above, the cover plate 901 can be provided with a number of through holes 912 aligned with corresponding holes 812 formed in the housing block 801 to facilitate a tight coupling therewith, for example, as shown in the top view 900A of the cover plate 901.

[0041] 10 shows a front view 1000A and a top view 1000B of an assembled ammonia sensor manifold assembly 1001 according to one implementation, where the housing block 801 and cover plate 901 are assembled as a modular unit. The ammonia sensor 1002 is disposed within the receptacle 810 such that the sensing portion 1004 protrudes into the hollow cylindrical space 806 extending between the openings 802 and 804, while the electrical interface portion 1006 of the sensor 1002 (shown without an associated electrical connector in this view) is exposed to facilitate external electrical connection. Depending on whether the incoming or outgoing outlet pipe portion is connected, either of the openings 802, 804 can operate as an inflow or outflow port similar to the arrangement of the trimethylamine sensor manifold assembly 1001 shown in FIG. 6.

[0042] 12, an example seal arrangement 1200 for the ammonia sensor manifold assembly of FIG. 7 is shown according to one implementation. An ammonia sensor 1202 is shown with a sensing portion 1204 and an electrical interface portion 1206 (electrical connectors or pins not specifically shown). As described in detail above, to provide a tight seal in the modular manifold assembly, a first O-ring seal 1208 is disposed around the body portion of the sensor 1202 proximate the sensing portion 1204 and a second O-ring seal 1210 is disposed around the body portion of the sensor 1202 proximate the electrical sensing portion 1206.

[0043] With regard to data acquisition and processing of sensor data, various arrangements may be deployed that generally involve sensor interface wiring, signal interconnect wiring, one or more analog / digital DAQ units, a sensor power supply system, and one or more optional USB hubs (e.g., for communicating with a remote host), regardless of the type or variety of sensors used, or whether the sensors have different electrical interface portions. Although example data acquisition and processing systems may have similar configurations and arrangements, a particular implementation may differ based on, for example, the sensor's electrical characteristics, sensing principle, electrical connector pinout, sensor sensitivity, etc. By way of example, an example ammonia sensor may have six electrical connectors or pins (e.g., TGS826) and an example trimethylamine sensor (e.g., TGS2603) may have four electrical connectors or pins, but may implement similar data acquisition and monitoring schemes in accordance with the teachings herein. In one implementation, example sensor interface wiring and signal interconnect wiring include standard AMP connectors, RJ-45 connectors, CAT-5 connectors, etc., although some arrangements may involve wireless connectivity. Bus technologies such as PCI (Peripheral Component Interconnect), PCI Express, PXI (PCI eXtensions Instrumentation), PXI Express, Ethernet, etc. may also be used in some DAQ arrangements. Analog voltage data from the sensor may be processed by the DAQ and provided to a computer implemented monitoring system where appropriate program logic or instructions may be executed by a processor to characterize the amount of by-products present in the exhaust stream. Depending on the process flow, electrical characteristics of the sensor, tooling conditions, etc., different thresholds may be established for different by-products, which may be used to determine whether a particular by-product is present in sufficient amounts to indicate a satisfactory HMDS reaction process. If a small amount of the benchmark by-product is detected, appropriate containment and corrective actions may be taken on the WIP wafer.

[0044] Although the ammonia and trimethylamine sensor manifold assemblies are described in detail above, various other sensors may be deployed in additional and / or alternative configurations in which a suitable modular sensor manifold assembly may be fabricated in accordance with the teachings herein. For example, organic solvent sensors, high VOC sensors, etc. may be deployed in combination with or independent of the ammonia and trimethylamine sensors in the exemplary process flow to sense, detect, measure suitable benchmark by-products and determine and / or identify appropriate control actions on WIP wafers. Also, depending on the form factors of the sensors deployed in a given arrangement, the exemplary sensor manifold assemblies may include housing blocks and / or cover plates of various sizes, shapes, form factors, etc., and various openings, sensor receptacles, and / or input and output openings may be designed with appropriate shapes, sizes, etc. to accommodate the appropriate sealing arrangements.

[0045] In addition, because process recipes can vary significantly within or across manufacturing facilities, depending, for example, on tool type and / or processing requirements, process thresholds for detected / monitored by-products in the exhaust stream can also vary considerably. In some process flows, satisfactory HMDS performance may produce 30-50 ppm ammonia and 10-15 ppm trimethylamine as by-products. In one implementation, a process "fault" point or threshold may be established when a 50% or greater reduction in these values ​​is detected. In other tool types implementing different recipes for HMDS applications, satisfactory performance may produce lower amounts of ammonia and trimethylamine, e.g., 15-20 ppm ammonia and 5-10 ppm trimethylamine. At such tooling conditions, a viable process threshold may be established when the monitored by-products fall below 25% of the expected output.

[0046] The example exhaust gas monitoring system described herein may be implemented with substantial flexibility, such that one implementation may include characterizing and modeling the behavior of an HMDS reaction chamber tool to determine a currently satisfactory operating point (i.e., "fingerprinting"), and then setting appropriate process thresholds or limits for different by-products accordingly near or to the operating point (e.g., in terms of absolute or relative ranges, percentages, etc.). Such thresholds may also depend on sensor sensitivity in some configurations. Thus, different thresholds may be implemented for the same benchmark by-product depending on process / tool ​​conditions.

[0047] 13A and 13B show a flow chart for an example method according to one implementation. Process flow 1300A may begin with applying an adhesion promoter in gas form (e.g., a hexaalkyldisilazane, such as hexamethyldisilazane (HMDS) vapor) to a semiconductor process wafer disposed in a reaction chamber, as shown in block 1302, for example, prior to applying a photoresist layer in a photolithography step of a process flow used to fabricate ICs in or on the semiconductor process wafer. In block 1304, an exhaust stream flowing from the reaction chamber is monitored to detect the presence of one or more byproducts (e.g., benchmark byproducts) of a reaction between the adhesion promoter, the semiconductor process wafer, and an associated surface layer. As shown in block 1306, in response to determining that the detected by-products are present in the exhaust stream in an amount above a corresponding threshold, the semiconductor process wafer proceeds to the next stage of the IC manufacturing process, which may involve applying an appropriate PR material using any known or heretofore unknown technique and process recipe depending on the layer being patterned, the spectral characteristics of the light / radiation used in photolithography for exposure (e.g., 436 nm ("g-line"), 405 nm ("h-line"), and 365 nm ("i-line"), X-ray, etc.). Process flow 1300B involves variations in which additional and / or alternative actions may be taken in response to determining that the benchmark by-products are not present in the exhaust stream or are present below a corresponding threshold, as shown in block 1322. For example, the process flow may involve at least one of, but not limited to, (i) terminating further processing of the semiconductor wafer (e.g., the semiconductor process wafer does not proceed to PR application), and / or (ii) designating the semiconductor process wafer for rework or scrap.

[0048] As mentioned above, an exemplary IC manufacturing flow may include several photolithography steps that may be performed during various stages of semiconductor wafer processing. Accordingly, an appropriate PR adhesion promoter tool and associated exhaust gas monitoring may be deployed at one or more stages of the manufacturing flow according to various examples described herein. In one implementation, each adhesion promoter tool and associated exhaust gas monitoring stage may involve detecting a specific benchmark by-product based on the appropriate surface preparation, a specific sensor type and corresponding manifold assembly, and a specific process recipe to achieve the respective reaction chamber operating point and applicable threshold value. Also, the exhaust gas monitoring scheme may vary depending on the wafer substrate material (e.g., Si, SiC, SiGe, GaAs, or organic semiconductor material, etc.), the surface layer material and composition, the adhesion promoter material (e.g., HMDS, non-HMDS, etc.), etc. Thus, the various examples provide an adaptable system for monitoring exhaust gases in a robust yet flexible manner that may be implemented in many manufacturing environments.

[0049] Also, depending on the number of conductive and insulating layers (e.g., polysilicon layers, metal layers, dielectric layers, etc.) to be patterned and added within an IC chip, it may be deployed at various stages of an IC manufacturing flow, including FEOL and BEOL stages. In general, the FEOL process flow can be considered the first part of IC manufacturing where the individual devices (e.g., transistors, capacitors, resistors, etc.) are patterned within a semiconductor wafer. FEOL generally includes IC processing up to but not including deposition of metal interconnect layers. For an exemplary CMOS process, by way of example, FEOL may include all the manufacturing steps required to form a fully isolated CMOS device, which may include wafer preparation, shallow trench isolation, n-well / p-well formation, gate formation, and source / drain formation. In an exemplary manufacturing flow involving multiple IC devices, a CMOS wafer may undergo as many as 10-50 photolithography cycles.

[0050] The BEOL process flow includes the second part of IC fabrication where individual devices are interconnected with one or more wiring layers (called metallization layers). The BEOL generally begins when a first metal layer is deposited on a patterned wafer (e.g., with isolated devices) from the FEOL that has undergone silicidation and pre-metal dielectric deposition. The interconnect metal layer (e.g., copper or tungsten layer) can be patterned following a photolithography cycle preceded by AP application and an emission monitoring process according to one implementation of the present specification. Since the BEOL can include several intermetal dielectric layers that separate the respective metal layers and form intermetal vias, multiple photolithography cycles can be implemented in the exemplary BEOL flow. Thus, in some implementations, suitable AP tools and related emission monitoring schemes can also be deployed at one or several metal levels of the BEOL process flow.

[0051] An example implementation herein advantageously enables direct monitoring of the HMDS reaction process based on detection of specified by-products, rather than monitoring the incoming gas (i.e., carrier gas), which provides only an indirect and often inadequate assessment of the reaction process. Example implementations provide the ability to detect potential defects in the PR bonding process in real time, so that immediate notification and correction of the defects can occur, thereby preventing large quantities of defective products and / or scrap events.

[0052] Although various implementations have been shown and described in detail, the claims are not limited to any particular implementation or example. None of the above detailed description implies that any particular component, element, step, operation, or function is essential so as to be included in the claims. When a phrase such as "at least one of A and B" or a phrase of equivalent import is described or set forth, this means "A only, B only, or both A and B." Reference to an element in the singular does not mean "one and only one" unless expressly so stated, but instead means "one or more." All structural and functional equivalents to the elements of the above implementations known to those skilled in the art are expressly incorporated herein by reference and are encompassed by the claims.

[0053] The order or sequence of acts, steps, functions, components, or blocks shown in any of the flowcharts shown in the figures of this description may be modified, changed, substituted, customized, or otherwise rearranged within a particular flowchart, including the deletion or omission of certain acts, steps, functions, components, or blocks. Also, acts, steps, functions, components, or blocks shown in a particular flowchart may be intermixed with acts, steps, functions, components, or blocks shown in other flowcharts, or may be inter-arranged or rearranged in other ways to achieve additional variations, modifications, and configurations of one or more processes for purposes of the present disclosure. Thus, those skilled in the art will recognize that the example implementations described herein may be practiced with various modifications and alterations within the spirit and scope of the claims appended below.

Claims

1. 1. A method of manufacturing an integrated circuit (IC), comprising: applying an adhesion promoter in gas form to a semiconductor wafer disposed in a reaction chamber prior to application of a photoresist layer in a photolithography process used in fabricating integrated circuits on the semiconductor wafer; monitoring an exhaust stream flowing from the reaction chamber to detect the presence of one or more by-products of a reaction between the adhesion promoter and the semiconductor wafer; in response to determining that a detected by-product is present in the exhaust stream in an amount above a corresponding threshold, proceeding with the semiconductor wafer to a next stage in IC manufacturing; The method includes:

2. 2. The method of claim 1 , The method further includes, in response to determining that a benchmark by-product is not present in the exhaust stream or is present below the corresponding threshold, performing at least one of: (i) terminating further processing of the semiconductor wafer; and (ii) designating the semiconductor wafer for rework.

3. 2. The method of claim 1 , The method, wherein the adhesion promoter comprises hexamethyldisilazane (HMDS) vapor carried in a nitrogen carrier gas supplied as an influent into the reaction chamber.

4. 4. The method of claim 3, The method further comprises heating the semiconductor wafer at a temperature in the range of about 70° C. to 150° C. for about 5 to 30 seconds.

5. 5. The method of claim 4, The method, wherein the one or more by-products include at least one of ammonia, trimethylamine, and one or more volatile organic compounds (VOCs).

6. 6. The method of claim 5, The method, wherein the exhaust stream is monitored by an ammonia sensor to detect the presence of ammonia in the exhaust stream.

7. 6. The method of claim 5, The method, wherein the exhaust stream is monitored with a trimethylamine sensor to detect the presence of trimethylamine in the exhaust stream.

8. 6. The method of claim 5, The method, wherein the exhaust stream is monitored by a VOC sensor to detect the presence of VOCs in the exhaust stream.

9. A method for fabricating an integrated circuit (IC), comprising: exposing the semiconductor substrate to an adhesion promoter in a reaction chamber; monitoring an exhaust stream flowing from the reaction chamber; if a reaction by-product of a reaction between the semiconductor substrate and the adhesion promoter is detected, proceeding with the semiconductor substrate to a later stage of fabricating the IC; A method comprising:

10. The method of claim 9, comprising: The method, wherein the adhesion promoter comprises hexamethyldisilazane (HMDS).

11. The method of claim 9, comprising: The method further comprises heating the semiconductor substrate at a temperature between about 70° C. and 150° C. for about 5-30 seconds while exposed to the adhesion promoter.

12. The method of claim 9, comprising: The method, wherein the reaction by-products include at least one of ammonia, trimethylamine, and one or more volatile organic compounds (VOCs).

13. The method of claim 9, comprising: The method further comprising exposing the semiconductor substrate to a vacuum prior to exposing the semiconductor substrate to an adhesion promoter.

14. The method of claim 9, comprising: The method, wherein the exhaust stream is monitored with a trimethylamine sensor to detect the presence of trimethylamine in the exhaust stream.

15. The method of claim 9, comprising: The method, wherein the exhaust stream is monitored by an ammonia sensor to detect the presence of ammonia in the exhaust stream.

16. The method of claim 9, comprising: The method, wherein the subsequent step includes forming a photoresist layer over the semiconductor substrate.

17. A method for manufacturing an integrated circuit (IC), comprising: Introducing a production wafer into a reaction chamber; exposing the production wafer to hexamethyldisilazane (HMDS) in the reaction chamber; subjecting the production wafer to a photoresist coating process only under conditions where a reaction by-product of a reaction between the production wafer and the HMDS is detected; A method comprising:

18. The method of claim 17, comprising: The method of claim 1, wherein the reaction by-product comprises ammonia.

19. The method of claim 17, comprising: The method wherein the presence of the reaction by-products is determined by a sensor exposed to an exhaust flow in gas form from the reaction chamber.

20. The method of claim 17, comprising: The method further includes patterning a photoresist layer produced by the photoresist coating process with a pattern representative of a material layer of the integrated circuit.

21. 1. A system comprising: a reaction chamber including a housing and an inflow port and an outflow port, the housing including a thermal plate for heating a semiconductor process wafer at a predetermined temperature for a predetermined amount of time; an inlet pipe coupled to the inflow port for supplying a photoresist adhesion promoter in gas form to the reaction chamber; an outflow pipe connected to the outflow port for discharging by-products from the reaction chamber; at least one gas sensor manifold assembly coupled to the outlet pipe for monitoring an exhaust flow from the reaction chamber to detect the presence of one or more by-products of a reaction between the photoresist adhesion promoter and the semiconductor wafer; Including, the system.

22. 22. The system of claim 21, the housing further comprising a perforated applicator coupled to the in-flow port for substantially uniformly distributing the photoresist adhesion promoter within the housing; The system, wherein the photoresist adhesion promoter comprises hexamethyldisilazane (HMDS) vapor in a nitrogen carrier gas.

23. 23. The system of claim 22, the one or more by-products include an ammonia by-product; The system, wherein the at least one gas sensor manifold assembly includes a first gas sensor manifold assembly including an ammonia sensor for detecting the ammonia by-product in the exhaust stream.

24. 24. The system of claim 23, the first gas sensor manifold assembly comprising: a housing block having an input opening and an output opening with a hollow space connecting the input opening and the output opening, the input opening being coaxially coupled to a first portion of the outlet pipe and the output opening being coaxially coupled to a second portion of the outlet pipe, the housing block including a receptacle having a receptacle portion opening into the hollow space, the receptacle configured to receive the ammonia sensor having a first body portion including a sensing portion and a second body portion including an electrical interface portion, the sensing portion protruding into the hollow space between the input opening and the output opening, the hollow space facilitating the passage of the exhaust flow between the first and second portions of the outlet pipe; a first O-ring seal disposed about the first body portion to seal the receptacle portion opening to the hollow space; a cover plate rigidly coupled to the housing block, the cover plate having an opening for exposing an electrical interface portion of the ammonia sensor to facilitate electrical connection with a data acquisition unit; Further comprising: a second O-ring seal dimensioned to seal the opening in the cover plate is disposed about a second body portion of the ammonia sensor, the second O-ring seal being compressed between the housing block and the cover plate.

25. 24. The system of claim 23, the one or more by-products include a trimethylamine by-product; The system, wherein the at least one gas sensor manifold assembly further includes a second gas sensor manifold assembly including a trimethylamine sensor for detecting trimethylamine by-product in the exhaust stream.

26. 26. The system of claim 25, the second gas sensor manifold assembly comprising: a housing block having an input opening and an output opening with a hollow space connecting the input opening and the output opening, the input opening being coaxially coupled to a first portion of the outlet pipe and the output opening being coaxially coupled to a second portion of the outlet pipe, the housing block including a receptacle having a receptacle portion opening into the hollow space, the receptacle configured to receive the trimethylamine sensor having a first body portion having a sensing portion and a second body portion having an electrical interface portion, the sensing portion protruding into the hollow space between the input opening and the output opening, the hollow space facilitating the passage of the exhaust flow between the first and second portions of the outlet pipe; a cover plate rigidly coupled to the housing block, the cover plate having an opening for exposing an electrical interface portion of the trimethylamine sensor to facilitate electrical connectivity with a data acquisition unit; Further comprising: an O-ring seal dimensioned to seal the opening in the cover plate is disposed about the second body portion of the trimethylamine sensor, the O-ring seal being compressed between the housing block and the cover plate.

27. 26. The system of claim 25, The system wherein the first and second gas sensor manifold assemblies are disposed in series along the outlet pipe.

28. 26. The system of claim 25, the outlet pipe is branched into a first parallel portion and a second parallel portion, the first gas sensor manifold assembly is coupled to the first parallel portion for detecting a first by-product in the exhaust stream, and the second gas sensor manifold assembly is coupled to the second parallel portion for detecting a second by-product in the exhaust stream.

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