A method and system for monitoring a degas chamber using a photoionization detector and a residual gas analyzer

Abstract

A method of sample analysis in a semiconductor fabrication tool includes performing a leak check of a process chamber at a first pressure using an RGA. The analysis process is stopped for a failed leak check and a semiconductor wafer is inserted into the process chamber if the leak check passed. The semiconductor wafer is cleaned in the process chamber by adding an inert gas into the process chamber to raise a pressure inside the process chamber to a second pressure, and heating the semiconductor wafer inside the process chamber. A PID sensor is structured to detect volatile compounds emitted from the semiconductor wafer and generate a failure signal if volatile compounds are detected above a predetermined level. The wafer is removed from the process chamber and the next manufacturing process commenced when volatile compounds detected by the PID sensor at or below a predetermined level.

Description

TITLEA METHOD AND SYSTEM FOR MONITORING A DEGAS CHAMBER USING A PHOTOIONIZATION DETECTOR AND A RESIDUAL GAS ANALYZER.CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application is related, and claims priority to, commonly-owned Provisional Patent Application Serial No.: 63 / 543,563, filed October 11, 2023, having the same title. The entire contents of said application is incorporated by reference as if disclosed herein in its entirety.TECHNOLOGICAL FIELD

[0002] This following disclosure relates generally to the field of semiconductor fabrication and more specifically a system and method for monitoring a degas chamber of a semiconductor fabrication tool using a photoionization detector and a residual gas analyzer.BACKGROUND

[0003] Semiconductor fabricating assemblies often include a degas chamber in which a degas process occurs. Generally, a degas process is a process of activating and removing gaseous , liquid and / or solid substances, such as moisture, photoresist and other contaminates from a semiconductor wafer through heating. The presence of these substances on the semiconductor wafer may prevent a thin film from being formed on targeted areas of a wafer or may change the characteristics of the resulting semiconductor junctions and electrical interconnections. The degas process is generally performed in a separate degas chamber that is fluidly connected or fluidicallycoupled to deposition or etch chambers of a semiconductor fabricating tool. In many modem degas chambers, the pressure of the degas operation is on the order of a few Torr of an inert gas where the inert gas helps transport heat to the wafer. A wafer temperature of a few hundred degrees Celsius is sometimes used. In order to reliably carryout the degas process, the degas chamber is pumped to low base pressure and preferably monitored for air leaks prior to adding inert gas or heating the wafer. The heating step of the degas process also provides an opportunity to check the wafer for residual photoresist and other contamination. Currently, mass spectrometers adapted for sampling at high pressures by means of differential pumping with or without sniffers are used to monitor such degas chambers. These devices can monitor for air leaks in the chamber at base pressure and also monitor for wafer contaminants at the higher pressures and temperatures used during the degas step; however these devices are very large, expensive, and complicated to use. Additionally, it is difficult to optimize them for both low pressures and high-pressure steps encountered in the degas chamber. Although a simple RGA — that is not differentially pumped - may be suitable for testing the chamber for leaks at base pressure, it is not able to be operated during higher pressures of the degas step. As a result, many semiconductor fabrication assemblies forego this monitoring step, which may compromise the quality of the final semiconductor product and may also increase waste due to large numbers of wafers being scrapped.

[0004] These are just some of the problems associated with current semiconductor fabrication tools and / or assemblies that use a degas process.SUMMARY

[0005] Aspects of the present disclosure are directed to embodiments of a vacuum immersion PID sensor including a housing and a sensor head partially positioned in the housing and open to a surrounding environment. The sensor head is structured to sample gases from thesurrounding environment. Tn some embodiments, the vacuum immersion PTD sensor further includes a control unit in electrical communication with the sensor head and an extension that is coupled to the housing at a first end and that is coupled to a support structure at an opposing end. The extension is structured to support the housing and position the housing proximate to a sample inside a process chamber.

[0006] In some embodiments, the process chamber includes a hot environment. In some embodiments of the vacuum immersion PID sensor, the support structure includes a portion of a residual gas analyzer. In some embodiments of the vacuum immersion PID sensor, the extension is structured to house electrical connections between the sensor head and the control unit. In some embodiments, the sample gases are emitted from a semiconductor wafer. In some embodiments, the vacuum immersion PID is constructed so that it can be located close to a sample source and survive a hot environment, such as temperatures of 200 °C or more, and not contaminate a semiconductor process.

[0007] Aspects of the present disclosure are directed to embodiments of a system for monitoring gases in a sample processing chamber at multiple pressures. In some embodiments, the system includes a PID sensor structured to analyze gas emissions from the sample, an RGA includung an RGA sensor structured to analyze gases in the chamber for detecting leaks, and a control unit in electrical communication with the PID sensor and the RGA. In some embodiments of the system, the controller is programmed to analyze the gases in the chamber using the RGA when a pressure of an environment surrounding the sample is below a threshold value. In some embodiments of the system, the controller is further programmed to analyze the gases in the chamber using the PID sensor when a pressure of an environment surrounding the sample is above a threshold value and deactivate the RGA when the pressure surrounding the sample is above thethreshold.

[0008] In some embodiments of the system, upon detecting an emission of one or more unexpected volatile compounds from the sample, the PID sensor is structured to transmit a signal to the control unit and the control unit controls a process in the chamber based on the signal transmitted by the PID sensor. In some embodiments of the system, the PID sensor further includes an extension extending from a first end to a second end, wherein the first end is structured to couple to the PID sensor, and wherein the extension is structured to position the PID sensor proximate to the sample. In some embodiments of the system, the extension is structured to house one or more electrical connections to the PID sensor. Some embodiments of the system further include at least one conduit structured to deliver the gases in the chamber from the sample to the PID sensor. In some embodiments of the system, the at least one conduit is a heated conduit. In some embodiments of the system, the PID sensor is deactivated when the pressure surrounding the sample is below the threshold value. In some embodiments of the system, the PID sensor is positioned in a conduit that connects to a process chamber. In some embodiments of the system, the process chamber is a degas chamber.

[0009] Aspects of the present disclosure are further directed to embodiments of a method of sample analysis in a semiconductor fabrication tool. In some embodiments, the method includes performing a leak check of a process chamber at a first pressure using an RGA, outputting an indication whether the process chamber passed or failed the leak check, stopping the analysis process if the leak check failed, and inserting a semiconductor wafer into the process chamber if the leak check passed. In some embodiments, the method further includes cleaning the semiconductor wafer in the process chamber. In some embodiments, the cleaning includes adding an inert gas into the process chamber to raise a pressure inside the process chamber to a secondpressure, and heating the semiconductor wafer using a heater positioned inside the process chamber. In some embodiments, the method further includes structuring a PID sensor to analyze an environment proximate to the semiconductor wafer to detect volatile compounds emitted from the semiconductor wafer, generating a failure signal if volatile compounds are detected above a predetermined level, and removing the wafer from the process chamber and proceeding to the next manufacturing process when volatile compounds detected by the PID sensor at or below a predetermined level.

[0010] Some embodiments of the method, further include structuring an extension to extend between a first end and a second end, structuring the first end of the extension to couple to the PID sensor, and structuring the second end to couple to a support. In some embodiments, the extension positions the PID sensor proximate to the semiconductor wafer. Some embodiments of the method further include structuring the process chamber as a degas chamber. In some embodiments, the failure signal includes at least one of an electronic signal, an audio signal, and a visual signal. Some embodiments of the method further include continuing to heat the semiconductor wafer for a predetermined period of time after generation of the warning signal. Some embodiments of the method further include deactivating the PID sensor when the pressure surrounding the sample is below the threshold value.

[0011] An embodiment of a system including a combination of a PID sensor for high pressure analysis and an RGA for low pressure analysis is provided where the PID sensor is structured for insertion close to a sample source. The system further includes a controller configured to operate the PID only at pressures above a threshold value and to operate the RGA only at pressures below a threshold value.

[0012] An embodiment of a method of degassing a semiconductor wafer includesperforming a quality check on the process chamber using a PTD and an RGA. The PID is immersed or positioned inside the process chamber proximate to the semiconductor wafer. The RGA utilizes the process chamber’s internal pumping system and conducts analysis at pressures below a threshold pressure value. The PID conducts analysis of emissions from the semiconductor wafer at pressures above a threshold pressure value.

[0013] Further aspects of the disclosure are directed to a vacuum immersion PID sensor including a housing and a sensor head partially positioned in the housing and open to a surrounding environment. The sensor head is structured to sample gases from the surrounding environment. In some embodiments, a control unit is in electrical communication with the sensor head. In some embodiments, an extension is coupled to the housing at a first end and coupled to a support structure at an opposing end. In some embodiments, the extension is structured support the housing and position the housing proximate to a sample inside a process chamber.

[0014] In some embodiments, the process chamber comprises a hot environment. Some embodiments of the vacuum immersion PID sensor further include a radiation source. In some embodiments of the vacuum immersion PID sensor, the support structure comprises a portion of a residual gas analyzer. In some embodiments, the sample is a semiconductor wafer. In some embodiments of the vacuum immersion PID sensor, the control unit is at least partially positioned in the housing.BRIEF DESCRIPTION OF DRAWINGS

[0015] A more particular description of the invention briefly summarized above may be had by reference to the embodiments, some of which are illustrated in the accompanying drawings. It is to be noted, however, that the appended drawings illustrate only typicalembodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. Thus, for further understanding of the nature and objects of the invention, references can be made to the following detailed description, read in connection with the drawings.

[0016] Fig. 1 schematically illustrates an embodiment of a portion of a semiconductor manufacturing assembly or tool including degas chamber.

[0017] Fig. 2 schematically illustrates an embodiment of a degas chamber monitoring system fluidly coupled to a degas chamber.

[0018] Fig. 3 A schematically illustrates another embodiment of a degas chamber monitoring system fluidly coupled to a degas chamber.

[0019] Fig. 3B schematically illustrates a close-up view of a PID sensor from the embodiment of Fig. 3A coupled to an extension and positioned proximate to a semiconductor wafer.

[0020] Fig. 4. schematically illustrates another embodiment of a degas chamber monitoring system where process gas is pumped from the degas chamber to a PID for analysis.

[0021] Fig. 5 graphically shows an embodiment of an emissions plume being emitted from a semiconductor wafer in a degas chamber and the spreading or dissipation of the plume over a period of time when the walls of the degas chamber are heated.

[0022] Fig. 6 graphically shows an embodiment of an emissions plume being emitted from a semiconductor wafer in a degas chamber and the spreading or dissipation of the plume over a period of time when the walls of the degas chamber are cooled.

[0023] Fig. 7 illustrates a flow chart of an embodiment of a method for monitoring a degas chamber using a photoionization detector and a residual gas analyzer.DETAILED DESCRIPTION

[0024] The following discussion relates to various embodiments of a system and method for monitoring a degas chamber of a semiconductor fabrication assembly or tool. It will be understood that the herein described versions are examples that embody certain inventive concepts as detailed herein. To that end, other variations and modifications will be readily apparent to those of sufficient skill. In addition, certain terms are used throughout this discussion in order to provide a suitable frame of reference with regard to the accompanying drawings. These terms such as “upper”, “lower”, “forward”, “rearward”, “interior”, “exterior”, “front”, “back”, “top”, “bottom”, “inner”, “outer”, “first”, “second”, and the like are not intended to limit these concepts, except where so specifically indicated. The terms “about” or “approximately” as used herein may refer to a range of 80%-125% of the claimed or disclosed value. With regard to the drawings, their purpose is to depict salient features of a system and method for monitoring a degas chamber of a semiconductor fabrication assembly or tool and are not specifically provided to scale.

[0025] Referring to Fig. 1, an embodiment of a degas chamber 10 is schematically depicted with a chamber wall 12 defining a chamber space 14. In some embodiments, a thermal support or hot chuck 16 is positioned in the chamber space 14 and a thermal wall or hot wall 18 is also positioned in the chamber space 14. In some embodiments, the hot wall 18 is positioned opposite the hot chuck 16. The hot chuck 16 is structured to support or accept a semiconductor wafer or wafer 50 deposited in or on the hot chuck 16 by a robotic arm 20, which may be positioned in another chamber 30. It should be reiterated that Fig. l is a schematic depiction to show a concept and that other embodiments may exist that include additional chambers and / or structures between, in and / or around chamber 30 and the degas chamber 10. In some embodiments, a load lock maybe positioned between the chamber 30 and the degas chamber 10. Tn some embodiments, the semiconductor wafer 50 is a 300 mm semiconductor wafer 50, but other sizes of wafer 50 are contemplated.

[0026] Turning to Figs. 2-4, an embodiment of a degas chamber monitoring system 100 (“system”) including a photoionization detector (PID) 150 is shown that is configured to detect unexpected volatile compounds coming off of the wafer 50 in a degas chamber 10. In some embodiments, the PID 150 may be similar to embodiments of the PID described in PCT / US2023 / 019041. Accordingly, in some embodiments, the PID 150 may generally comprise a sensor head 152 and a sensor controller 154, which may include a plurality of electronic components and connections. In some embodiments, the sensor controller 154 may include a power source and / or connections to direct power to the sensor head 152, one or more sensors, processors, memory units, or other such electronic components to facilitate operation and control for the PID 150. The sensor head has been previously described in detail. In some embodiments, the PID sensor head 152 may further include a radiation source 156, which may be comprised of a single gas or multiple different gases contained within a space. In some embodiments, the radiation source 156 comprises contained Kr gas at least partially surrounded by glass (or other similar material). The Kr gas generates a plasma within the glass. In some embodiments, the radiation source 156 is positioned outside of the degas chamber 10 or otherwise at least partially positioned in an environment that is isolated from the environment of the degas chamber 10. In some embodiments, an ionization chamber 157 defined by the sensor head 152 is exposed at one end to the environment of the degas chamber 10. Photons created by the Kr plasma enter the ionization chamber and collide with gas molecules present therein. Analysis of the gas proceeds according to methods disclosed in described in PCT / US2023 / 019041. In some embodiments, thePTD 150 is in electrical communication with a controller 200 that may be part of the control electronics of the semiconductor fabrication tool, or may be separate, but in electrical communication with the control electronics of the semiconductor fabrication tool. In some embodiments, Kr could be replaced by Xe, Ar, or another gas depending on the energy required for the generated ionizing photons, as is well known in the art of photoionization detectors.

[0027] In the embodiments of the system 100, 110, 120 shown in Figs. 2-3 A, and Fig. 4, the PID 150 works in conjunction with a residual gas analyzer (RGA) 170, which is in pneumatic communication with the degas chamber 10 through one or more conduits 160 or passageways. In this embodiment, the PID 150 and the RGA 170 are in electrical communication with each other and with a controller 200. The controller 200 may be a controller for the semiconductor fabrication tool. In the embodiment of the degas chamber monitoring system 100 of Fig. 2, the PID 150 is positioned as close to the degas chamber 10 as possible without being positioned inside the chamber space 14. In some embodiments, the RGA 170 further includes an RGA sensor 172 and an RGA controller 174. In some embodiments, the RGA sensor 172 is positioned inside the conduit 160 that pneumatically connects the RGA 170, the PID 150 and the degas chamber 10 such that gases in the degas chamber 10 may be transported to the PID sensor head 152 and the RGA sensor 172 in Fig. 2.

[0028] Referring to the embodiment of the degas monitoring system 110 of Figs. 3 A and 3B, in some embodiments, the PID 150 and the RGA 170 are also in electrical communication with each other and with a controller 200 similar to embodiments previously discussed. In some embodiments, the electrical communication is facilitated via an ethernet switch190. In some embodiments, the electrical communication includes data transmission. In the degas chamber monitoring system 110 of Figs. 3A and 3B, in some embodiments, the PID 150 ispositioned in the chamber space 14 and as close to the wafer 50 as possible. As shown, the PID 150 is coupled to an extension 155, which supports the PID 150, houses electrical connections 158 between the PID sensor head 152 and the PID controller 154. Furthermore, the extension 155 enables the PID 150 to be positioned proximate to the wafer 50. Similar to other embodiments, the RGA 170 further comprises an RGA sensor 172 and an RGA controller 174. In some embodiments, the RGA sensor is positioned inside a conduit 160 or passage that pneumatically connects the RGA 170, the PID 150 and the degas chamber 10 such that gases in the degas chamber 10 may be transported to the RGA sensor 172 in Fig. 3 A. In some embodiments, the inside of the extension 155 defines an inner space that is sealed from the surrounding process environment and may be held at atmospheric pressure (about 760 torr).

[0029] In some embodiments, prior to the start of a wafer degas process, the wafer 50 is moved by robotic means 20 through a load lock and into the degas chamber 10. In some embodiments, the degas chamber 10 is at a first pressure that is low enough for safe operation of the RGA 170. In some embodiments, the first pressure is less than 5e-4 torr. In some embodiments, the RGA 170 is then operated to check for the presence of air components as a means of leak checking the degas chamber 10. If the leak check process determines that no air components are present in the degas chamber 10, then the degas process commences.

[0030] In some embodiments, during the degas process, the degas chamber 10 is flooded with an inert gas to increase the pressure inside of the degas chamber 10 to a second pressure and the wafer 50 is heated. In some embodiments, the second pressure is around 7 torr. The function of the inert gas is to aid in transferring heat from a heater 19 (Fig. 4) positioned in the degas chamber 10 to the wafer 50. During this process, volatile compounds, such as hydrocarbons from, for example, residual photoresist, and moisture are emitted from or removedfrom the wafer 50 as shown schematically in Fig. 3B. In some embodiments, the PID 150 selectively detects these hydrocarbons while “ignoring” the outgassing water. The detection of these hydrocarbons is important because their presence typically indicates a fault in an earlier process, such as incomplete removal of photoresist. Monitoring for these hydrocarbons allows the degas process to continue until they fall to an acceptable level, or for the processing of the particular wafer 50 to be stopped and the cause of the elevated levels to be investigated. Overall, detection of volatile compounds, especially unexpected volatile compounds, may prevent the current wafer 50 from becoming expensive scrap and / or contaminating other processes further downstream in the semiconductor manufacturing process.

[0031] Figure 5 shows a graphical representation of a concentration of substances being emitted from the wafer 50 in relation to time and distance from the wafer 50. The simulation of Fig. 5 assumes uniform contamination of the wafer 50. As can be seen, at 0.1 seconds after the degas process starts, the emissions concentration is at a maximum and the emission plume is positioned within about 20cm from the center of the wafer 50. As the degas process continues from 5 seconds to 20 seconds after the process begins, the peak concentration decreases, however the plume has become more diffuse throughout the degas chamber 10, spreading up to and beyond 40cm from the center of the wafer 50. In this embodiment, the chamber wall is a hot wall 18 that enables encourages the plume to remain in a gaseous state at the 20 second mark. The Figure 6 shows a similar simulation as Fig. 5, but in Fig. 6, the chamber wall is cooled such that the concentration at the wall drops to zero. With cold walls, the sampling tubes, or a sensor outside the chamber may see or register no emission. The same result may occur if the compounds decompose on the walls of the degas chamber 10.

[0032] In both examples it is clear that the closer that the PID sensor head 152 ispositioned relative to the wafer 50, the sooner an emission from the wafer 50 is detected, and the higher the detection sensitivity will be. Accordingly, it is conceivable that, if the PID sensor head 152 is placed too far from the wafer 50, then no emission will be detected due to low or zero concentration. Therefore, as discussed above and in some of the embodiments shown, the PID 150 is mounted to an extension 155 such that the PID 150 is able to be positioned within the chamber space 14 of the degas chamber 10. In some embodiments, the extension 155 supports the PID 150, houses PID electrical connections, and enables the PID 150 and particularly the PID sensor head 152 to be positioned particularly close to the semiconductor wafer 50 within the chamber space 14 (Figs. 3A, 3B, 5 and 6). Detection of an emission of volatile compounds from the wafer 50 can be the result of a fault in a step of the semiconductor manufacturing fabrication process. In some embodiments, upon detection of an emission of one or more unexpected volatile compounds from the wafer 50, the PID 150 may be structured to generate a signal and transmit said signal to the semiconductor fabrication tool via the controller 200. In this manner one or more semiconductor manufacturing processes may be adjusted such that excess wafer scrap is prevented.

[0033] In some embodiments of the system 110 120, such as those shown in Figs. 3 A, 3B, and 4, the degas chamber 10 is brought down to a first pressure and the RGA 170 is used at this first pressure to look for air components in the degas chamber 10 to determine whether there are any leaks. In some embodiments, the first pressure is around 10'4torr. In the event that a leak is suspected, the location of the leak can be determined by monitoring the RGA 170 output while spraying helium around the outside of the degas chamber 10 and the leak detection process is performed again by the RGA 170. In some embodiments, the first pressure is low enough such that any helium gas leaked into the degas chamber 10 is spread quickly throughout the degas chamber 10 and through any conduit 160 to the RGA sensor 172. Therefore, the RGA 170 doesnot need to be positioned close to the wafer 50 in order to detect the leak. Accordingly, in some embodiments, the system 110, 120 is not only configured to detect hydrocarbon emissions from the wafer 50 at high pressures (e.g. about 7 torr), but is further able to perform a leak detection process at a low pressure, such as the first pressure. In some embodiments, the controller 200 may be structured to obtain a pressure reading from a pressure gauge or from the PID 150 itself, for higher pressures, such as a second pressure (e.g. pressures higher than the first pressure), or from the RGA 170 for lower pressures, for example around 10'4torr or less, and regulate the operation of the PID 150 and RGA 170 based on the obtained pressure reading. In some embodiments, the controller 200 is structured to turn on the RGA 170 when the degas chamber 10 is pumped down to a predetermined low pressure, such as the first pressure (e.g. 10’4torr) while also turning off the PID 150. Similarly, in some embodiments, the controller 200 may be structured to turn off the RGA 170 when the pressure inside the degas chamber 10 rises above the predetermined low pressure, such as to the second pressure, while also turning on the PID 150.

[0034] In some embodiments of the system 110, prior to the degas step, the wafer 50 is inserted into the degas chamber 10 and the degas chamber is pumped to the first pressure or base pressure of about 10'4torr or less. During this period volatile solvents (such as acetone or other solvents carrying the photoresist) coming off of the wafer 50 may be detected by the RGA 170. At this stage, the chamber space 14 and the passageway 160 are configured to contain a rarified inert gas, such as argon, and are maintained at a second higher pressure, e.g., 7 torr. Once the semiconductor wafer 50 is deposited onto the hot chuck 16, it is heated by the hot chuck 16 and the hot wall 18, or a heater 19, such as a showerhead heater by means of heat transported by the rarified gas for a predetermined amount of time before being removed from the degas chamber 10 by the robotic arm 20. While the degas chamber 10 and the passageway 160 are at the secondpressure, volatile solvents (such as acetone or solvents carrying the photoresist) coming off of the wafer 50 may be detected by the PID 150. The second pressure of the degas chamber 10 and the passageway 160 prevents fast diffusion of the gas in the degas chamber 10 to the PID 150, so the closer it is positioned to the wafer the higher and faster its response to degassed contaminants will be.

[0035] The PID 150 may be positioned at a variety of locations relative to the wafer50 as may be required by a particular use, including outside of the degas chamber 10. In some embodiments, at least part of the system 120 is self-contained in a housing 122 that can be installed onto a semiconductor fabrication tool. In an embodiment shown in Fig. 4, when the PID 150 is positioned away from the degas chamber 10, the environment of the degas chamber 10, and specifically the environment surrounding the wafer 50, may be pumped though a sniffer tube 164 to the PID 150 for analysis. In such an installation, the pump lines 162, conduits 166 and the sniffer tube 164 may be heated. In some embodiments, the radiation source 156 of the PID sensor head 152 is at least partially positioned inside the housing 122. The ionization volume 157 is open to the gas environment that is pumped through the sniffing tube 164 such that molecules of said gas environment collide with photons emitted from the radiation source 156. The gas environment is analyzed by the PID 150 in a manner similar to that described in PCT / US2023 / 019041. The RGA 170 may operate as described in previous embodiments. In some embodiments, the RGA sensor 172 is positioned in a conduit 160 or passageway that enables gases in the degas chamber 10 to move from the degas chamber to the RGA sensor 172. In some embodiments, the PID control 154 and the RGA control 174 may be positioned inside the housing 122. In some embodiments, the controller 200 may further be positioned inside the housing 122 and in electrical communication with the PID 150 and the RGA 170.

[0036] An embodiment of a method 300 of monitoring a degas chamber will now be discussed with reference to Fig. 7. This method may be practiced with the embodiments of the system discussed above. In some embodiments, preventative maintenance (pm), e.g., cleaning, of the degas chamber 10 is performed at step 302. After preventative maintenance is completed, the degas chamber 10 is pumped down to the first pressure (about 10’4Torr or less), at which point a leak test is performed at step 304. In some embodiments, the leak test is performed by releasing helium gas around the outside of the degas chamber 10. In some embodiments, the RGA 170 is then used to detect helium and / or air components in the degas chamber 10. Detection by the RGA of helium and / or air components in the degas chamber 10 may be an indication of a leak in the degas chamber 10 resulting in failure of the leak test. In some embodiments, if a leak test has failed, then an alarm or indicator is output to the user at step 306 and the entire process may be ended or as shown in Fig. 7, may be reset. In some embodiments, if the leak test is successful (i.e., a leak is not detected by the RGA 170), then the semiconductor wafer 50 is inserted into the degas chamber 10 at step 308. The degassing process then begins at step 310. In some embodiments of the degassing process, the pressure in the degas chamber 10 is then increased to a second pressure (e.g., about 7 torr) by the addition of an inert gas and the wafer 50 is heated. As the wafer 50 is heated, volatile compounds, such as hydrocarbons, and moisture may be released or emitted from the wafer 50 resulting in a clean wafer 50. In some embodiments, a PID 150 (a vacuum immersion PID) sensor is used to detect said hydrocarbon emissions at step 312. In some embodiments, the information obtained by the PID 150 is then transmitted to the controller 200 and / or the semiconductor fabrication tool where it is analyzed determined whether changes to the fabrication process are required. If unexpected volatile emissions are detected by the PID 150, then a failure is indicated at step 314 and the process may end 316 or, may revert back to one of the previoussteps, for example the preventative maintenance step 302. If no unexpected volatile emissions are detected by the PID 150 at step 312, then the wafer 50 is removed at step 318. Some embodiments of the method may further include measuring an emission from the wafer 50 at the first pressure before the degas process begins and detecting a leak in the degas chamber 10 after the conclusion of the degas process.

[0037] It is envisioned that the disclosed PID sensor and associated method of monitoring may be used in other industries where the cleanliness of a component and / or emissions from a component need to be monitored, such as in vacuum furnaces. In such instances, using a mass spectrometer would be cost prohibitive. While the embodiments of the PID sensor 150 and method disclosed use a static pressure to monitor emissions, it is possible to use the PID sensor 150 and disclosed method in situations where the pressure varies. Moreover, the operating pressures disclosed are exemplary embodiments and do not limit operation at other pressures.

[0038] While the present invention has been particularly shown and described with reference to certain exemplary embodiments, it will be understood by one skilled in the art that various changes in detail may be effected therein without departing from the spirit and scope of the invention that can be supported by the written description and drawings. Further, where exemplary embodiments are described with reference to a certain number of elements, it will be understood that the exemplary embodiments can be practiced utilizing either less than or more than the certain number of elements.

Claims

CLAIMS1. A vacuum immersion PID sensor comprising: a housing; a sensor head partially positioned in the housing and open to a surrounding environment, wherein the sensor head is structured to sample gases from the surrounding environment; a control unit in electrical communication with the sensor head; and an extension coupled to the housing at a first end and coupled to a support structure at an opposing end, wherein the extension is structured to support the housing and position the housing proximate to a sample inside a process chamber.

2. The vacuum immersion PID sensor of claim 1, wherein the process chamber comprises a hot environment.

3. The vacuum immersion PID sensor of claim 1, wherein the support structure comprises a portion of a residual gas analyzer.

4. The vacuum immersion PID sensor of claim 1, wherein the extension is structured to house electrical connections between the sensor head and the control unit.

5. The vacuum immersion PID sensor of claim 1, wherein the sample gases are emitted from a semiconductor wafer.

6. A system for monitoring gases in a sample processing chamber at multiple pressures, comprising: a PID sensor configured to analyze gas emissions from the sample; an RGA comprising an RGA sensor configured to analyze gases in the chamber for detecting leaks; and a control unit in electrical communication with the PID sensor and the RGA, the control unit programmed to:analyze the gases in the chamber using the RGA when a pressure of an environment surrounding the sample is below a threshold value; and analyze the gases in the chamber using the PID sensor when a pressure of an environment surrounding the sample is above a threshold value and deactivate the RGA when the pressure surrounding the sample is above the threshold.

7. The system of claim 6, wherein, upon detecting an emission of one or more unexpected volatile compounds from the sample, the PID sensor is configured to transmit a signal to the control unit, wherein the control unit controls a process in the chamber based on the signal transmitted by the PID sensor.

8. The system of claim 7, where the PID sensor further comprises an extension extending from a first end to a second end, wherein the first end is structured to couple to the PID sensor, and wherein the extension is structured to position the PID sensor proximate to the sample.

9. The system of claim 8, wherein the extension is structured to house one or more electrical connections to the PID sensor.

10. The system of claim 6, further comprising at least one conduit structured to deliver the gases in gases in the chamber from the sample to the PID sensor.

11. The system of claim 9, wherein the at least one conduit is a heated conduit.

12. The system of claim 6, wherein the PID sensor is deactivated when the pressure surrounding the sample is below the threshold value.

13. The system of claim 6, wherein the PID sensor is positioned in a conduit that connects to a process chamber.

14. The system of claim 13, wherein the process chamber is a degas chamber.

15. A method of sample analysis in a semiconductor fabrication tool comprising: performing a leak check of a process chamber at a first pressure using an RGA; outputting an indication whether the process chamber passed or failed the leak check; stopping the analysis process if the leak check failed; inserting a semiconductor wafer into the process chamber if the leak check passed; cleaning the semiconductor wafer in the process chamber, wherein the cleaning comprises, adding an inert gas into the process chamber to raise a pressure inside the process chamber to a second pressure, and heating the semiconductor wafer using a heater positioned inside the process chamber; structuring a PID sensor to analyze an environment proximate to the semiconductor wafer to detect volatile compounds emitted from the semiconductor wafer; generating a failure signal if volatile compounds are detected above a predetermined level; and removing the wafer from the process chamber and proceeding to a next manufacturing process when volatile compounds detected by the PID sensor at or below a predetermined level.

16. The method of claim 15, further comprising structuring: an extension to extend between a first end and a second end; the first end of the extension to couple to the PID sensor; and the second end to couple to a support, wherein the extension positions the PID sensor proximate to the semiconductor wafer.

17. The method of claim 15, further comprising structuring the process chamber as a degas chamber.

18. The method of claim 15, wherein the failure signal comprises at least one of an electronic signal, an audio signal, and a visual signal.

19. The method of claim 15, further comprising continuing to heat the semiconductor wafer for a predetermined period of time after generation of the failure signal.

20. The method of claim 15, further comprising deactivating the PID sensor when the pressure surrounding the sample is below the predetermined value.

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