Monitoring system for hostile environment

A monitoring system for monitoring a parameter of a hostile environment is provided within the interior of a sealed chamber. The chamber has a wall and an access port extending through the wall to the chamber exterior. The monitoring system includes a flexible, generally tubular, elongated housing having a distal end, a proximal end and a interior. The housing is made of a non-porous, corrosive resistant material. The distal end of the housing includes a sealed window and a sensor, which may be a borescope or camera, for sensing a parameter or for capturing an image within the hostile environment. The proximal end of the housing is sealingly secured to the chamber wall at the port so that the interior of the housing is accessible through the port. The interior of the housing includes a transmission media for transmitting an output signal of the sensor from the distal end of the housing to the proximal end of the housing and through the port. A monitor located outside of the chamber and connected to the transmission media receives and displays a representation of the sensor signal.

BACKGROUND OF THE INVENTION

The present invention relates generally to a monitoring system and, more particularly, to a monitoring system for monitoring or measuring one or more parameters, performing visual inspections or otherwise obtaining information from within a harsh or hostile environment such as within the interior of a sealed semiconductor wafer processing chamber.

There are many situations in which it is desirable to have the ability to measure or monitor one or more parameters or make visual inspections within a harsh or hostile environment. For example, it is desirable to have the ability to monitor one or more parameters, such as temperature and pressure, within the environment of a semiconductor wafer processing chamber. The environment within such a semiconductor wafer processing chamber, particularly during the processing of semiconductor wafers, includes high vacuum pressures. The use of existing, standard, unprotected monitoring equipment and/or techniques within such a semiconductor wafer processing chamber or any other such harsh or hostile environment is ineffective because most existing monitoring equipment is simply not constructed to withstand the severe pressures encountered within such a semiconductor wafer processing chamber and/or the severe temperatures, pressures and other environmental factors present in other such harsh or hostile environments. The present invention overcomes the problems of the prior art by providing a flexible, generally tubular elongated protective housing made of a non-porous, hermetically sealed, corrosive resistant material for containing the sensitive measuring and/or monitoring equipment employed for measuring or monitoring one or more parameters within a semiconductor wafer processing chamber or other such harsh or hostile environment. The present invention is particularly useful in calibration, inspection and maintenance within a semiconductor wafer processing chamber.

BRIEF SUMMARY OF THE INVENTION

Briefly stated, the present invention comprises, in one embodiment, a monitoring system for monitoring a parameter of a hostile environment within the interior of a sealed chamber. The chamber has a wall with an access port extending through the wall to the chamber exterior. The monitoring system comprises a flexible, generally tubular, elongated housing having a distal end, a proximal end and an interior. The housing is made of a non-porous, hermetically sealed, corrosive resistant material. The distal end of the housing contains a sealed window and a sensor for sensing a parameter of the hostile environment through the window. The proximal end of the housing is sealingly secured to the chamber wall at the access port so that the interior of the housing is accessible through the port. The interior of the housing includes a transmission media for transmitting an output signal of the sensor from the distal end of the housing to the proximal end of the housing and through the port. A monitor is located outside of the chamber and is connected to the transmission media for receiving the sensor signal and displaying a representation of the sensor signal.

In another embodiment, the present invention comprises an optical monitoring system for transmitting images from a hostile environment within the interior of a sealed chamber to the chamber exterior. The chamber has a wall and an access port extending through the wall. The monitoring system comprises a flexible, generally tubular, elongated housing having a distal end, a proximal end and an interior. The housing is made of a non-porous, hermetically sealed, corrosive resistant material. The distal end of the housing includes a sealed window and the proximal end of the housing is sealingly secured to the chamber wall at the access port so that the interior of the housing is accessible through the port. The interior of the housing includes a transmission media for transmitting images of the interior of the chamber obtained through the window from the distal end of the housing to the proximal end of the housing and through the port. A monitor is located outside of the chamber and is connected to the transmission media for receiving and displaying the images of the interior of the chamber.

In yet another embodiment, the present invention comprises an optical monitoring system for transmitting images from a hostile environment within the interior of a sealed chamber to the chamber exterior. The chamber has a wall with an access port extending through the wall. The monitoring system comprises a flexible, generally tubular, elongated housing having a distal end, a proximal end and an interior. The housing is made of a non-porous, hermetically sealed, corrosive resistant material. The distal end of the housing includes a sealed window and the proximal end of the housing is sealingly secured to the chamber wall at the access port so that the interior of the housing is accessible through the port. A camera is positioned within the distal end of the housing to record images of the interior of the chamber through the window. The interior of the housing includes a transmission media for transmitting the images of the interior of the chamber as recorded by the camera from the distal end of the housing to the proximal end of the housing through and the port. A monitor is located outside of the chamber and is connected to the transmission media for receiving and displaying the recorded images of the interior of the chamber.

In a further embodiment, the present invention comprises an optical monitoring system for transmitting images from a hostile environment within the interior of a sealed chamber to the chamber exterior. The chamber has a wall with an access port extending through the wall. The monitoring system comprises a flexible, generally tubular, elongated housing having a distal end, a proximal end and an interior. The housing is made of a non-porous hermetically sealed, corrosive resistant material. The distal end of the housing includes a sealed window and the proximal end of the housing is sealingly secured to the chamber wall at the access port so that the interior of the housing is accessible through the port. The interior of the housing includes a borescope for transmitting images of the interior of the chamber obtained through the window from the distal end of the housing to the proximal end of the housing and through the port. A monitor is located outside of the chamber and is connected to the borescope for receiving and displaying the images of the interior of the chamber.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the drawings, wherein like numerals are used to designate like components throughout the several figures, there is shown inFIG. 1, a diagrammatic representation of a portion of a semiconductor wafer processing chamber100within which is positioned a monitoring system10in accordance with a first preferred embodiment of the present invention. The semiconductor wafer processing chamber100, which in the present configuration is shown as being generally cylindrical, includes a wall102comprised of a generally vertically extending, generally cylindrical portion and generally circular upper and lower portions which together function to establish the generally sealed chamber100. The materials employed and the methods employed for forming the chamber100are well known to those of ordinary skill in the art and are not necessary for a complete understanding of the present invention. Contained within the chamber100are the equipment and components (not shown) necessary for establishing the environment required for processing semiconductor wafers. Such equipment and components are also well known to those of ordinary skill in the art and further details regarding the structure and operation of such equipment and components are not necessary for a complete understanding of the present invention. One such component which is contained within the chamber100is a robot assembly104, which is primarily employed for the purpose of transferring semiconductor wafers into and out of the chamber100through a suitable slot-like sealed doorway (not shown) and for moving the wafers to various processing stations (not shown) within the chamber100. The robot assembly104is comprised of a moveable base member106, a wafer holding assembly108and a pair of supporting linkage members110, which are employed for moving the remainder of the robot assembly104to the chamber doorway and to various locations within the chamber100to facilitate processing of semiconductor wafers. The robot assembly104is of a type well known to those of ordinary skill in the semiconductor wafer processing art. Further details concerning the structure and operation of the robot assembly104are not necessary for a complete understanding of the present invention.

The foregoing description relates to a semiconductor wafer processing chamber100of the type diagrammatically illustrated byFIG. 1and well known to those of ordinary skill in the semiconductor wafer processing art. Such chambers are commercially available from well known manufacturers, including Applied Materials, Inc. Further details regarding the structure and operation of the chamber100are available from the manufacturers and a variety of publicly available sources and are not necessary for a complete understanding of the present invention. As is also understood by those of ordinary skill in the art, during a semiconductor wafer processing operation, the interior112of a semiconductor wafer processing chamber100of the type described and shown is at temperatures in the range of 25° C. ±10° and is subject to vacuum pressures in the range of 10−7Torr which functions to create a harsh or hostile environment, which effectively precludes the use of standard, unprotected sensing or monitoring equipment and techniques, including a video camera or other viewing equipment. The inability to use such sensing equipment and techniques and/or a video camera or other viewing equipment within such a semiconductor wafer processing chamber100makes it much more difficult to fully know the values of certain parameters within the chamber which are needed to better control the processing of semiconductor wafers therein. The present invention overcomes the difficulties associated with the prior art by providing a system for measuring or monitoring one or more parameters or obtaining visual images from within a hostile or harsh environment such as the environment present within a semiconductor wafer processing chamber100during the processing of semiconductors.

A first embodiment of the present invention as illustrated inFIGS. 1-4comprises an optical monitoring system10for transmitting images from the hostile environment within the interior112of the sealed semiconductor processing chamber100to the chamber exterior. In the present embodiment, the optical monitoring system10is comprised of a flexible, generally tubular elongated protective housing12having a first or distal end14and a second or proximal end16. The protective housing12, which is used to protect a sensor, camera or the like from the harsh environment within the chamber100, is made of a non-porous, hermetically sealed, corrosive resistant material. As shown inFIG. 1, the housing12comprises a shroud or sheath which is preferably formed of a stainless steel bellows, thereby making the housing12generally flexible for movement of at least the distal end14about the chamber100in a manner which will hereinafter be described. The bellows is preferably of the helical type but could be of the discrete ring type or some other type. It will be appreciated by those of ordinary skill in the art that other materials may alternatively be employed, including other metals or metal alloys, polymeric materials, such as polypropylene, composite materials and the like. Accordingly, the particular material employed for making the protective housing12should not be considered to be a limitation on the present invention. In addition, the protective housing12need not be in the form of a bellows, as long as it is sufficiently flexible and gas tight. Preferably, the thickness of the protective housing12is sufficient to provide the needed protection in the particular environment within which the monitoring system10is employed. In the case of a semiconductor wafer processing chamber100, the thickness of the preferred stainless steel bellows is in the range of 0.010 to 0.015 inch. In the present embodiment, the bellows has an outside diameter or about ⅝ inch and a length of about three feet. However, the dimensions of the bellows may vary depending on the application.

As best shown inFIGS. 2 and 3, the housing12further includes a generally tubular member18which extends outwardly from the distal end14of the bellows portion. A sensor housing20is secured to the distal end of the tubular member18. Both the tubular member18and the sensor housing20are preferably made of a high strength, non-porous, hermetically sealed, corrosive resistant material, such as stainless steel. However, other materials, including polymeric materials, may alternatively be employed. Preferably, the proximal end of the tubular member18is secured to the distal end14of the bellows portion of the housing12using brazing, welding, an adhesive or any other suitable securing means which provides a gas tight connection. Similarly, the sensor housing20is secured to the distal end of the tubular member18using brazing, welding, an adhesive or any other suitable method providing a gas tight connection.

The sensor housing20is generally in the form of a parallelepiped and includes a sealed window22on at least one surface. The window22is generally flat and is formed of a material which is resistant to the hostile environment within the chamber100but which also has high light transmission, particularly in the infrared, visible and ultraviolet ranges. Preferably, the window22is formed from a single crystal synthetic sapphire but it could be formed of glass, quartz, a polymeric material or any other light transmissive material which is resistant to the environment within the chamber100. In the preferred embodiment, the window22is generally circular, is formed of synthetic sapphire and is secured by brazing within a suitably sized generally circular opening within one surface of the sensor housing20. If desired, some other method may be employed for securing the window22within the opening of the sensor housing20including using fusion, an adhesive, or any other suitable securing method or device which provides a gas tight connection. In this manner, a hermetically sealed protective environment is established within the housing12as a result of the materials employed in making the bellows portion of the housing12, tubular member18, sensor housing20and window22and as a result of having all such components being secured together with gas tight connections and hermetically sealed as described above. In the present embodiment, the sensor housing20is generally in the shape of a flat parallelepiped. However, it will be appreciated by those of ordinary skill in the art that the sensor housing20could have some other shape, for example, it could be cylindrical, or of any other suitable shape. In addition, in the present embodiment, the window22is generally circular. It will be apparent to those of ordinary skill in the art that the window22could be square, rectangular or of any other suitable shape. Also, in the presently preferred embodiment, the generally rigid tubular member18extends between the distal end14of the bellows portion of the housing12and the sensor housing20. It will be appreciated by those of ordinary skill in the art that, if desired, the sensor housing20could be secured directly to the distal end14of the bellows portion of the protective housing12.

As best shown inFIG. 4, the chamber100includes an opening or access port114extending the through the wall102between the exterior and interior112thereof. In the illustrated embodiment, the access port114is generally circular and is located on the upper or top surface of the chamber wall102. It will be appreciated by those of ordinary skill in the art that the access port114could extend through the chamber wall102at any other suitable location. In the present embodiment, the access port114is generally circular and has a predetermined diameter which is at least slightly greater than the outer dimension of the bellows portion of the protective housing12. It will be appreciated by those of ordinary skill in the art that the size and shape of the access port114may vary from the size and shape as shown and described. Thus, it should be clearly understood that the size, shape and location of the access port114should not be considered to be a limitation upon the present invention. In addition, while in the present embodiment, a single access port114is shown, It will be appreciated by those of ordinary skill in the art that multiple access ports (not shown) could be positioned at multiple locations along the chamber wall102.

The optical monitoring system10further includes a port housing24positioned on the exterior surface of the chamber wall102to generally cover and enclose the access port114. As best shown inFIGS. 1 and 4, the port housing24is generally cylindrically shaped with a diameter at least slightly greater then the diameter of the access port114and with a generally open first end26and a second end28, which is generally closed with the exception of a generally circular hole or opening30extending generally through the radial center thereof. The first end26of the port housing24includes a generally, radially outwardly extending annular flange32, which is employed for engaging and securing the port housing24to the exterior surface of the chamber wall102. The annular flange32includes a plurality of generally radially spaced, generally circular openings34extending therethrough and a generally annular sealing groove36on the surface which faces the exterior surface of the chamber wall102. The chamber wall102includes a plurality of openings116extending therethrough and surrounding the access port114, the chamber wall openings116being circumferentially spaced in a generally circular pattern which corresponds to the pattern of the openings34extending through the annular flange32. In this manner, when the port housing24is placed on the exterior surface of the chamber wall102over the access port114with the openings34on the annular flange32aligned with the openings116of the chamber wall102, a plurality of fasteners, such as bolts38and corresponding nuts40may be employed for securing the port housing24to the chamber wall102. Prior to securing the port housing24to the chamber wall102, an annular sealing ring42, such as an elastomeric O-ring, is installed within the sealing groove36. In this manner, the port housing24may be hermetically sealed to the chamber wall102surrounding the access port114. It will be appreciated by those of ordinary skill in the art that the port housing24may be sealingly secured to the exterior of the chamber wall102by clamping, the use of an adhesive or any other manner known to those of ordinary skill in the art to provide a hermetic seal between the port housing24and the chamber wall102. Preferably, the port housing24is made of a non-porous, corrosive resistant high strength material. In the present embodiment, the port housing24is made of stainless steel. However, other materials, including other metals and metal alloys, polymeric materials, composite materials or the like may alternatively be employed for forming the port housing24. In addition, the port housing24could be of some other shape, if desired.

A generally tubular coupling member44extends through the opening30of the second end28of the port housing24and into the port housing interior. The first or upper end of the coupling member44sealingly engages the port housing opening30with a gas tight, but rotatable fit. The proximal end16of the protective housing12is secure to the second or lower end of the coupling member44. Preferably, the proximal housing end16is secured to the coupling member44using brazing, fusion, an adhesive or in some other manner well known to those of ordinary skill in the art to provide a permanent, gas tight connection therebetween. In this manner, the coupling member44and thus the housing12, while supported within the port housing24may rotate with respect to the port housing opening30to facilitate movement of the protective housing12within the chamber100in a manner which will hereinafter be described. In an alternative embodiment, the coupling member44is permanently and non-rotatably secured within the port housing opening30. If desired, an arrangement, other than the coupling member44may be employed for rotatably or non rotatably supporting the proximal end16of the housing12within the port housing24with a gas tight connection.

The optical monitoring system10as thus far described provides a hermetically sealed, safe environment for a sensor or other device which may be moved to various locations within the chamber100in a manner which will hereinafter be described. Thus, a complete sealed path is established from the exterior of the chamber100through the port housing opening30, the coupling member44and the bellows portion, tubular member18and sensor housing20of the protective housing12so that sensors or other devices can be positioned within the sensor housing20inside of the chamber100without being exposed to the harsh environment within the chamber100.

It will be appreciated by those of ordinary skill in the art that a variety of different sensors could be installed within the protected environment of the housing12, as thus far described. Such sensors could include, for example, a temperature sensor, preferably of the infrared type commercially available from various manufacturers including Mikron of Northern New Jersey, a pressure sensor, preferably of the infrared type commercially from various manufacturers and an oxygen sensor, such as laser RAMAN sensor commercially available from various manufacturers, including Kaiser Optics of Ann Arbor, Mich., a spectrographic chemical analysis sensor commercially available from various manufacturers, including Custom Sensor of Wisconsin, a level sensor or the like. Any sensor or group of sensors which may be employed are preferably positioned within the sensor housing20proximate to the sealed window22for performing the requisite sensing task. A suitable transmission media, such as one or more electrical wires could extend from each such sensor and within the protective environment through the sensor housing20, tubular member18, flexible portion of the protective housing12and port housing24to the exterior of the chamber100where the proximal end of any such transmission media could be secured to a suitable electrical or electronic device, such as a display, computer, or the like for collecting, processing, analyzing, monitoring or displaying plots or other representations of the electrical signals received from the sensor.

In the preferred embodiment as illustrated byFIGS. 1-3, an optical sensor, such as a borescope50, is employed. The borescope50may be of the flexible or rigid type, depending on the particular application. In the present embodiment, the borescope50is of the flexible lensed type and is commercially available from a variety of sources, including Olympus International of Mitchell Field, N.Y. As shown in phantom inFIGS. 1 and 2, the distal or viewing end of the borescope50extends into the sensor housing20with the viewing portion52of the borescope50generally aligned with and facing the sealed window22. A light source (not shown) may also be incorporated within or may be secured to the borescope50. In this manner, the borescope50may sense or obtain images of the interior of the chamber100through the window22. The transmission media of the borescope50, in the present embodiment, a coherent fiber optic bundle54, extends from the viewing portion52within the sensor housing22through the tubular member18, bellows portion of the protective housing12and port housing24and into a suitable control box56(shown schematically inFIG. 1). The control box56includes elements (such as, lenses and a camera) well known to those of ordinary skill in the art for converting optical images received from the borescope50into electrical signals which are then passed along a wire or cable to a suitable video monitor58for display to a user.

In an alternate embodiment, instead of a borescope50, a camera could be employed. The camera may be of the video type well known to those of ordinary skill in the art and may be of the infrared, visible spectrum or ultra violet type. The camera could be a UGA, an SVGA, an XGA or MEGA pixel camera and the resolution of the camera could vary depending upon the application. Preferably, the camera is of the complimentary metal-oxide semiconductor (CMOS) type, but it could be a change coupled device (CCD) or any other type. In the present embodiment, a CCD camera available from Olympus International of Mitchell Field, N.Y. is employed. Preferably, the camera includes a light source to facilitate capturing images in low light conditions. Signals from the video camera are transmitted by the transmission media, in the form of one or more electrical wires or cables which extend from the sensor housing20, through the tubular member18, bellows portion of the protective housing12and port housing24and are connected to a suitable video monitor58for displaying to a user images obtained by the video camera through the sealed window22. In this manner, conditions within the interior112of the chamber100may be viewed and monitored

Regardless of whether the sensor is comprised of a borescope50, video camera or some other sensor as described above, the distal end14of the protective housing12, with or without the tubular member18, is preferably secured to the base member106of the robot assembly104, at least on temporary basis. In this manner, the robot assembly104, in addition to performing its normal duties within the semiconductor wafer processing chamber100, can be used for moving the sensor housing20with the sensor, borescope or camera therein to various locations within the chamber100. The monitoring system10may thus be employed for monitoring conditions, as well as to provide optical viewing at various locations throughout the semiconductor wafer processing chamber100. A suitable clamp (not shown) clip (not shown) or any other suitable fastening member or material may be employed for securing the tubular member18and/or sensor housing20to the base member106of the robot assembly104. In the embodiment shown inFIG. 1the sensor housing20extends upwardly, at an angle from the robot base member106for enhanced viewing.

Referring now toFIGS. 5 and 6, there is shown a monitoring system210in accordance with an alternate embodiment of the present invention. As with the above-described embodiment, the monitoring system210is comprised of a flexible, generally tubular elongated bellows-like portion of the protective housing212, which is substantially the same as the protective housing12as described above. The bellows-like portion of the protective housing212has a first or distal end214which is secured to a sensor housing220. However, unlike the sensor housing20of the above-described embodiment, the sensor housing220of the present embodiment is generally cylindrically shaped and is formed of a generally tubular, generally continuous window222. The window222is preferably made of one of the same materials employed in making the window22of the above-described embodiment. A first or proximal end of the window222A is secured to the distal end214of the bellows-like portion of the protective housing212in substantially the same manner as described above in connection with the first preferred embodiment to provide a gas tight seal therebetween. The second or distal end of the window222B is enclosed by a cap member224. Preferably, the cap member224is secured to the distal end222B of the window222in the same manner as described above in connection with the first embodiment to provide a gas tight seal therebetween. By providing a sensor housing220formed of a generally continuous tubular window222, a borescope250installed therein may be rotated 360° so that the optical window252of the borescope may capture images at virtually any desired angle or location. As with the above-described embodiment, images captured by the borescope250are transmitted out of the chamber100by a fiber optic bundle254. Preferably, the end cap224is made of stainless steel or some other high strength metal, metal alloy or polymeric material.

As best shown inFIG. 6, the present embodiment includes additional components which may be employed for more particularly controlling the environment within the interior of the sensor housing220. A second flexible, generally tubular elongated housing312is provided within the interior of the bellows-like portion of the primary protective housing212to create a generally annular space313therebetween. The inner housing312includes a distal end314which is secured to a plug member316in the annular space313at the proximal end222A of the window222. The plug member316which is generally annular and is preferably made of stainless steel or a polymeric material, includes a plurality of circumferentially spaced, generally circular openings318extending completely therethrough. In this manner, fluid, under pressure, may be provided from the proximal end of the protective housing212within the annular space313. As shown by the arrows onFIG. 6, the fluid flows along and out of the annular space313through the plug member openings318, into the sensor housing220and returns to the proximal end of the housing212within the inner housing313. The fluid may be a cooling fluid, a heating fluid or some other fluid employed for controlling the environment within the interior of the protective housing212and particularly the sensor housing220where the sensor, camera, etc. is located. In addition to controlling the environment within the sensor housing220, the fluid controls the environment within the rest of the protective housing212as it passes through the annular space313. In one embodiment, the fluid flow is provided at approximately 20 lbs. per square inch at approximately 12 cubic ft. per hour. By controlling the environment within the interior of the protective housing212and particularly within the interior of the sensor housing220, the monitoring system210is able to function to provide images and/or to monitor or measure parameters in more hostile environment. If desired, the fluid may be used to increase the pressure within the housing12to decrease the pressure differential between the interior and exterior of the housing12.

In a further alternate embodiment (not shown), the sensor, or at least a distal end of the sensor extends through a sealed opening within the sensor housing20or220to provide direct access to the interior of the chamber100.