Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
  • G01L9/00—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means
  • G01L9/0041—Transmitting or indicating the displacement of flexible diaphragms
  • G01L9/0076—Transmitting or indicating the displacement of flexible diaphragms using photoelectric means
  • G01L9/0077—Transmitting or indicating the displacement of flexible diaphragms using photoelectric means for measuring reflected light
  • G01L9/0079—Transmitting or indicating the displacement of flexible diaphragms using photoelectric means for measuring reflected light with Fabry-Perot arrangements
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
  • G01L11/00—Measuring steady or quasi-steady pressure of a fluid or a fluent solid material by means not provided for in group G01L7/00 or G01L9/00
  • G01L11/02—Measuring steady or quasi-steady pressure of a fluid or a fluent solid material by means not provided for in group G01L7/00 or G01L9/00 by optical means
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
  • G01L7/00—Measuring the steady or quasi-steady pressure of a fluid or a fluent solid material by mechanical or fluid pressure-sensitive elements
  • G01L7/02—Measuring the steady or quasi-steady pressure of a fluid or a fluent solid material by mechanical or fluid pressure-sensitive elements in the form of elastically-deformable gauges
  • G01L7/08—Measuring the steady or quasi-steady pressure of a fluid or a fluent solid material by mechanical or fluid pressure-sensitive elements in the form of elastically-deformable gauges of the flexible-diaphragm type
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
  • G01L9/00—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means

Definitions

• the invention relates to a pressure measuring cell arrangement with an optical membrane pressure measuring cell according to the features of patent claim 1 and to a method for producing a pressure measuring cell arrangement according to the features of patent claim 24.
• a diaphragm pressure measuring cell For high-resolution pressure measurement applications with high corrosion resistance to the media to be measured, in particular gases, a diaphragm pressure measuring cell was created, preferably for vacuum applications, which consists entirely of corrosion-resistant materials such as metal oxides, in particular an Al2O3, which is now used very successfully commercially.
• a known arrangement of this type has been published in USP 6,591,687, which is in its entirety an integral part of the invention described below.
• the presented there capacitive vacuum cell (CDG) is for example made entirely of a ceramic, in particular Al2O3. This achieves very high corrosion resistance and long-lasting reproducibility. Only in areas where sealing is required or where Throughputs are provided in small quantities other materials than Al2O3, unless the AI2O3 is welded without adding foreign material.
• the cell consists of a first plate-shaped housing body, over which a membrane is sealingly arranged in the edge region, so that it encloses a reference vacuum space.
• a second housing body On the side facing away from the reference vacuum space, a second housing body is likewise arranged so as to be sealingly closed at the edge area, so that a measuring vacuum space is formed there.
• This measuring vacuum chamber is provided with a connection for the supply of the medium to be measured.
• the surfaces of the first housing body and of the membrane, which form the reference vacuum space are coated in an electrically conductive manner, for example with gold, and form the electrodes of the capacitance measuring cell. The electrodes in turn are led out, for example through the first housing body or through the sealing area in the edge zone.
• the substantially parallel electrode surfaces have a spacing in the range of 2 microns to 50 microns.
• the sealing of the membrane in the edge region relative to the two housings is preferably carried out by welding, for example by laser welding. Very suitable and easy to use but is also a glass solder, which is also quite good corrosion resistance. Another possibility of the sealing connection is also to diffusively connect housing parts, for example in the green body stage, when it comes to completely avoid Al2 ⁇ 3-foreign material.
• This arrangement of the measuring cell essentially allows a symmetrical structure, which avoids any tension in the housing. This is particularly important in order to achieve a high measuring sensitivity and to realize low measuring pressures with high accuracy and reproducibility. This also makes it possible to use a very thin membrane of ceramic, which is mandatory if the measuring cell lower vacuum pressures than 100 mbar, and especially lower than 10 mbar, reliable with capacitive ceramic all-ceramic
• membrane thicknesses of 10 microns to 1000 microns necessary, with membrane thicknesses of 30 microns to 120 microns are preferred in order to achieve a very good resolution.
• Such a vacuum measuring cell has a first housing body and a membrane, each made of Al 2 O 3 ceramic or sapphire.
• the membrane is planar with an outer edge joined by a first seal to the first housing body to form a reference vacuum chamber.
• a nozzle connects the vacuum measuring cell with a medium to be measured.
• a transparent optical window is formed with a first partially reflecting surface on the inner, membrane-facing side, and at least the central portion of
• Membrane has a second reflective optical surface positioned opposite the first reflective surface. Except for
• Reference vacuum chamber is disposed opposite the window and spaced therefrom an optical fiber to supply or remove light to and from the membrane surface.
• a pressure difference between the two Different sides of the elastic membrane causes the bending of the membrane, whereby the length of the optical cavity changes accordingly.
• Light is focused through the sapphire housing or window onto the semireflective membrane surface from where it is collected and analyzed after passing through the interference phenomenon over multiple reflections between the two mirrors using one of several available methods (eg, Fizeau interferometer (FISO Inc.), white light polarization interferometer (OPSENS Inc.), Michelson interferometer, spectrometer, ...), whereby the length of the optical cavity and thus the pressure difference across the membrane is determined.
• Fizeau interferometer FISO Inc.
• OPSENS Inc. white light polarization interferometer
• Michelson interferometer spectrometer
• the measuring cell arrangement is thus part of a Fabry-Perot interferometer detection or analysis arrangement.
• the thickness of the membrane together with its free diameter and the desired maximum bend define the pressure range to be used.
• the membrane diameter may be 11 mm, for example, and its thickness may be 300 ⁇ m.
• Preferred ranges for the membrane diameter are 5.0 mm to 80 mm, preferably 5.0 mm to 40 mm, and the membrane thickness is in the range of 10 ⁇ m to 10 mm, preferably in a range of 10 ⁇ m to 1.0 mm, in particular for vacuum applications, and preferably in a range of 600 ⁇ m to 9 mm for high pressure applications.
• the preferred sensor cell described above has a single crystal sapphire window or a single crystal sapphire body with a sapphire membrane to facilitate external optical readout, e.g. B. to allow by means of a ball lens. An optical fiber can then be used to transmit the signal from the site to a readout unit.
• a disadvantage of using pure sapphire in the sensor cell is its price - machined single crystal sapphire is very expensive.
• the combination of sapphire and ceramic Al 2 O 3 introduces a small thermal expansion coefficient (CTE) mismatch which, for example, can cause temperature drift behavior problems. To reduce this effect, proper crystal alignment is required, which is a costly and time consuming process. If third, one with a Ceramic body connected crystal window is used, increase the mechanical tolerance requirements for the parallelism of the optical cavity.
• external optics such as B. ball lenses used to focus the light on the membrane. Due to different thermal expansion coefficients of the materials used, there is the possibility of shifting the measuring point on the membrane or the diffraction of the light beam. As a result, the system can show unstable behavior. In addition, a large number of components are required, making the manufacture of such a sensor cell expensive.
• an optical membrane pressure measuring cell is described in the patent application US 12 / 163,303, in which an optical fiber for Lichtein- and off-coupling is integrated into the membrane in a housing body of the pressure measuring cell.
• the sensor ODG sensor
• an optical fiber is connected directly to the housing body.
• the connection of the fiber with ceramic, the ceramic-ceramic bond and the formation of a suitable Fabry-Perot cavity are made by special adhesion sealing processes.
• the movement of a pressure-indicating membrane is determined by white light or short-coherence interferometry (WLI).
• Such a pressure measuring cell has a first housing body and a membrane arranged in the vicinity of the housing body, both of which are made of ceramic.
• the diaphragm has an outer edge connected to the first housing body to create a reference pressure chamber.
• a second housing body made of ceramic material is opposite to the membrane and is connected to the outer edge of the membrane, wherein the second housing body together with the membrane forms a pressure measuring chamber.
• the second housing body has a connecting piece for connecting the pressure measuring cell with a medium to be measured.
• the first housing body, the second housing body and the diaphragm are sealingly connected to each other at the outer edge of the diaphragm, and a hole is formed in a central portion of the first housing body and extends through the first housing body and at least into the central region of the diaphragm and the hole opposite a surface of the membrane is formed as a first optically reflective surface.
• An optical fiber is disposed in the hole and sealingly secured to guide light to the surface of the membrane.
• the end of the fiber extends at least to the surface of the first housing body and is formed as a second optical reflecting surface connecting the surface such that there is an optical cavity between the fiber end and the reflecting surface, comprising a measuring section for determining the extent of deformation of the membrane forms and is part of a Fabry-Perot interferometer.
• this measuring cell together with the readout unit forms a compact unit, a membrane pressure measuring cell arrangement.
• the electrical signal is picked up directly behind the first housing body and electronically processed there by the shortest possible route.
• the paths must be short because of the low signal levels to be processed in order to keep external interference sufficiently low at the required high signal resolutions.
• This side of the measuring cell is located on the atmospheric side together with the evaluation electronics.
• the measuring cell arrangement forms a structural unit which is communicatively connected to the process space via the connection piece on a process chamber wall.
• optical membrane pressure measuring cell ODG
• the optical signal is picked up directly behind the first housing body and then forwarded with an optical fiber to a signal evaluation unit. Between optical fiber and the signal analyzer longer distances are possible here.
• the coupling of the optical fiber takes place precisely just behind the measuring cell and this output Coupling arrangement is an integral part of the entire measuring cell arrangement similar to the previously described capacitive design.
• the measuring cell arrangement as a whole forms a structural unit which, as in the case of the capacitive arrangement, is communicatively connected to the process space via the connection piece on a process chamber wall.
• the long-known other vacuum pressure measuring cells such as Pirani, Penning, Bayard Alpert, Inverted Magnetron and Massenspektro- meter, which are not based on a membrane assembly, as previously described as compact units.
• Such a whole Bauein- unit is also often arranged via a socket with flange on the process chamber wall.
• the pressure measuring cell arrangement comprises an optical membrane pressure measuring cell, which contains a housing body made of metal oxide with one of them arranged at a small distance, sealingly arranged in the edge region membrane, such that between a reference pressure space is formed, and that this membrane a process space with the measured is exposed to gaseous medium, wherein the housing body has at least in the center region an optically transparent window, the surface of which is designed to be partially reflecting on the side to the reference pressure space and the, this facing surface of the membrane is formed optically reflective at least in the center region, and that outside the reference pressure space, Opposite and spaced from this window forming an optical path, a signal receiving unit is provided with an optical fiber for coupling and decoupling of light on the surface of the membrane, such that dad A measurement path is used to detect deflections of the diaphragm with a signal evaluation unit, whereby a Fabry-Perot interferometer arrangement is formed.
• the process chamber is finally surrounded by a chamber wall against the atmosphere, and the process space is limited with a release agent at least in some areas, such that between the separating means and the chamber wall spaced therefrom, a climatic chamber is formed, wherein the signal receiving unit is arranged optically passing through the chamber wall and the separating means comprises at least in the region of the optical path optically transparent means, such that between the Membrane pressure measuring cell and the signal recording unit is an optical connection.
• the pressure measuring cell arrangement thereby no longer forms a compact measuring cell unit, such as a component component, as has hitherto been customary.
• the measuring cell arrangement according to the present invention is subdivided into an optical membrane pressure transducer with an associated optical signal receiving unit spaced therefrom, which can be positioned at the intended and suitable locations in and on a process chamber.
• the diaphragm pressure transducer can now be positioned within the process chamber directly where relevant relevant process conditions to be measured occur.
• the signal pickup unit is arranged on the wall of the process chamber and communicates optically with the membrane pressure transducer and leads the signal from the process space to the atmosphere side for further processing with a signal evaluation unit.
• the arrangement forms a Fabry - Perot interferometer measuring device.
• a climatic chamber for decoupling the process space.
• Release agents may be screen-like planar elements or even closed walls, wherein in the region of the light path, a window is provided for its passage. This window can, depending on the requirement and dimensioning of the arrangement, consist of a simple hole opening or of a transparent material.
• This climate chamber can cover only a partial area or enclose the entire process space, such as a further chamber.
• a different climate is preferably produced than in the process room for effective decoupling. For example, other gases and / or pressures are set there, for example, with additional pumping. This can also be done only in partial areas, for example via generated pressure levels or partial pumping.
• the membrane pressure transducer can be remotely operated in this way, spaced from the signal receiving unit, without this in addition to media such electrical supply or electronic signal processing, must be supplied, which is important in the often difficult process conditions or would no longer be feasible.
• processes are often operated with very aggressive, corrosive gases.
• high temperatures can occur.
• Even strong fluctuations in these conditions can cause problems.
• the optical readout of the membrane pressure transducer signal is not affected by such harsh conditions, and the diaphragm pressure transducer can be brought close to the desired, important process core. As a result, and with the aid of the additional climate chamber, very accurate and high-resolution pressure measurements can also be realized in critical areas of the process.
• Fig. 1a In cross-section, a membrane pressure transducer with optically transparent
• a membrane pressure transducer with housing body made of optically transparent material, which also forms windows for the light beam;
• Fig. 1c in cross section a membrane pressure transducer in which the housing body and the membrane is formed of optically transparent material;
• Fig. 1d A schematic representation of the light reflection in the membrane pressure transducer for the representation of the interference principle
• 2a shows in cross-section a pressure measuring cell arrangement according to the invention with sieve-like separating means for forming a separate air conditioning space
• Fig.2b in cross section a pressure measuring cell arrangement according to the invention with a wall as a release agent and with a built-in window to form a climatic chamber
• 3 shows in section a preferred example of a preferred vacuum process plant with a plant chamber and a further chamber disposed therein which separates the process space and forms a separating air space between the two chambers, according to the invention, an optical diaphragm pressure transducer on the chamber wall of the process chamber the process is disposed opposite exposed and this is optically communicating with a arranged on the system chamber signal recording unit;
• FIG. 4 In section, a system arrangement similar to the representation in FIG. 3 with a plurality of interleaved chambers, the process spaces enclosed and with an external air conditioning chamber and the process chambers associated membrane pressure transducers with the associated signal recording units arranged on the investment chamber.
• a pressure measuring cell arrangement has an optical membrane pressure transducer 23, which is placed with its membrane at the processing location and is thus directly exposed to the process area of interest and optically communicates with a signal receiving unit 32 in communicating connection, which is arranged in the plant chamber wall 30, which the atmosphere concludes, as shown schematically in Figures 1 to 4 and for example.
• such a pressure measuring cell arrangement comprises an optical membrane pressure transducer 23 which comprises a housing body 1 comprising at least one of the materials of a metal oxide, SiO 2 or SiC and a membrane 5 arranged at a small distance and sealingly arranged in the edge area.
• a reference pressure space 8 is formed therebetween, and that this membrane 5 is exposed to a process space 12, 34 with the gaseous medium to be measured
• the housing body 1 has an optically transparent window 3 at least in the center area, whose surface is on the side to the reference pressure space 8 out as a partially reflecting mirror 4 is formed and the, this facing surface of the membrane 5 at least in the center region is optically reflective, and that outside the reference pressure chamber 8, opposite and spaced from this window 3 forming an optical path 9, a signal receiving unit 32 with an optical fiber 22 is provided for coupling and decoupling light onto the surface of the diaphragm 5, such that a measuring path is thereby formed for detecting deflections of the diaphragm 5 with a signal evaluation unit 24, whereby a Fabry-Perot interferometer arrangement is formed.
• the process space 12, 34 is surrounded by a chamber wall 30 against the atmosphere 10 towards concluding, and the process space 12, 34 is limited with a release agent 25, 31 at least in partial areas, such that between the release agent 25, 31 and the thereof spaced apart chamber wall 30, a climatic chamber 11, 33 is formed, and the signal receiving unit 32 is arranged on the chamber wall 30 optically passing and the release agent 25, 31, at least in the region of the optical path 9 optically transparent means 25a, such that between the membrane pressure transducer 23 and the signal receiving unit 32 is an optical connection for transmitting the optical pressure signal.
• Such a pressure measuring cell arrangement with an optical membrane pressure transducer 23 is particularly suitable for measuring gas media at high pressure and in particular for vacuum.
• the housing body 1 is preferably round and plate-shaped. This is sealingly connected along its edges to a membrane 5 and is positioned at a distance from the housing body 1, such that between a reference pressure chamber 8 is formed, which is preferably a vacuum chamber.
• the distance between the two surfaces is normally set directly during the assembly by means of the sealing material 2, which is arranged between the diaphragm edge and the housing body edge. In this way, a completely flat housing plate 1 can be used and the membrane can deflect or move depending on the applied external pressure.
• the housing body contains or consists of a metal oxide, SiO 2, SiC, or glass or mixtures thereof.
• the housing body preferably consists of a metal oxide, in particular of aluminum oxide (Al 2 O 3 ). Al 2 O 3 of the crystalline form sapphire of high purity is particularly suitable.
• the housing body 1 can consequently be designed as a ceramic plate.
• the membrane 5 contains or consists of one of the materials, such as SiC, SiO 2 or preferably a metal oxide or mixtures thereof. It is advantageous if the metal oxide is an alumina, preferably the crystalline form sapphire of high purity.
• This measuring pressure chamber then has an opening which communicates with the medium of the process to be measured.
• unwanted interference such as charge carrier bombardment from a plasma process, be shielded.
• membrane side for other or additional measures are provided instead of this second housing plate such as sieve-like arrangements, hoods, nozzles, covers, baffles, etc.
• the seal 2 at most on both sides of the membrane defined according to the above description, the distance of the housing or the body 1 relative to the membrane 5.
• This seal 2 is for example and preferably a Glass solder, which is easy to handle and can be applied for example by screen printing.
• the melting or sintering temperature of the glass paste is preferably in the range of 630 0 C to 800 0 C.
• a preferred membrane pressure transducer with an outer diameter of 38 mm (more preferably the range 5-80 mm, especially preferably 5-40 mm) and a free membrane Inner diameter of 30 (preferred range 4-75) mm is the distance of the membrane 5 to the housing body 1, in the range of 2 .mu.m to 200 .mu.m, preferably 2 .mu.m to 50 .mu.m, and particularly preferred is a range of 12 .mu.m to 35 .mu.m.
• the housing body 1 has a thickness of 2 mm to 10 mm thick.
• a possible second housing body is, for example, in the same thickness range.
• the membrane 5 has a thickness in the range of 10 .mu.m to 1000 .mu.m, preferably from 30 .mu.m to 800 .mu.m.
• the flat unevenness of the membrane 5 is advantageously not more than 10 .mu.m, preferably not more than 5 .mu.m.
• the housing body 1 has at least in the center region an optically transparent window 3, the surface of which is formed on the side of the reference pressure chamber 8 as a partially reflecting first mirror 4 and the surface facing the membrane 5 at least in the center region opposite to the surface of the membrane 5 a second optically reflective surface 6 is formed, and preferably at least in the central region of the membrane 5.
• These mirror surfaces 4, 6 may be formed as a coating with a reflective film forming a mirror layer 4, 6.
• a coating may preferably be on the membrane surface of the second mirror 6 are formed with a Glaslotddling which is at high temperature, for example in a range from 700 0 C to 800 0 C, fired to produce a glazed surface as a reflecting surface, which forms the desired mirror of high quality.
• This concept of forming a mirror through a glass point is particularly advantageous because the mirror is easy to produce and withstands high temperatures without degrading the high reflectivity quality required in the mirror surface thus formed.
• the first mirror 4, designed as a partially reflecting can be produced without any coating, depending on the material used of the housing body 1, provided that this material in the region of the mirror 4 and the window 3 allows a suitable optical surface quality, for example by suitable processing, such as polishing and / or lapping.
• Particularly suitable here are materials such as glass, quartz (SiO 2 ), but especially sapphire.
• the membrane 5 for the at least partially reflecting region has, for example, a coating, preferably a coating that reflects as well as possible.
• the inner surface of the at least partially transparent housing part 1 or the window 3 is provided for example with a partially transparent coating, preferably with a semi-transparent coating.
• the formation of the reference pressure chamber 8, the cavity, with the opposing optically active surfaces must meet certain quality requirements for reading the signal according to the interference principle in order to achieve good Signalwerfe.
• the optically effective surfaces should be formed as parallel as possible.
• the angle deviation ⁇ of the two surfaces of the window 3 and the angular deviation ⁇ of the membrane surface and the angular deviation ⁇ of the partially reflecting region of the membrane surface should not exceed the total yield of 0.05 rad.
• the housing body 1 can at least partially consist of an aluminum oxide, preferably of the sapphire form, and this part should preferably be in the center region to form an optically transmissive window 3.
• An optically transparent window 3 can also be arranged as a transparent insert body within the housing body 1, for example the material of the housing body 1 itself is not sufficiently transparent, as shown in FIG. 1a.
• the window 3 is made of suitable transparent materials, such as preferably glass, quartz or sapphire.
• the window 3 as a separate insert part is vacuum sealingly connected in the center region of the housing part 1 with a seal. If the housing body 1 itself consists of a suitable optically transparent material, this also forms the window 3 for the light beam 9 to be coupled in, which is supplied via the optical path 9a, and a separate window part 3 is then not necessary, as shown in FIG. 1b.
• Both the membrane 5, as well as the housing body 1 may consist of optically transparent or non-transparent materials of the aforementioned material group.
• FIG. 1c shows a preferred embodiment for a membrane pressure transducer 23 in which both the membrane 5 and the housing body 1 are made of optically transparent material, such as, for example, and preferably made of sapphire.
• the reference pressure chamber 8 is provided with a correspondingly suitable reference pressure depending on the pressures to be measured. Vacuum gauging systems are provided with a vacuum and at high pressures above 1 bar, correspondingly adapted higher reference pressures can be provided. The pressure in the reference pressure chamber 8 is consequently set appropriately defined via a feed line in the housing body 1, which is then closed again with a cover 7.
• the optical membrane pressure transducer 23 forms part of a Fabry-Perot measuring arrangement and can now be positioned according to the invention with a high degree of freedom at the desired measuring location of the process.
• Light 9 is focused through the sapphire housing 1 and through the window 3 with the semi-reflective surface 4 on mirror surface 6 of the membrane surface, from where it after passing through the interference phenomenon over several reflections R and transmissions T between the two mirrors 4, 6 using one of several available methods, collected and analyzed (e.g., Fizeau Interferometer (FISO Inc.), White Light Polarization Interferometer (OPSENS Inc.), Michelson Interferometer, Spectrometer, Certainly, the length of the optical cavity and thus the pressure difference across the membrane is determined.
• the cell assembly is thus part of a Fabry-Perot interferometer detection or analysis arrangement.
• the light beam 9 is conducted to the system chamber wall 30 via a signal receiving unit 32 arranged there from the atmosphere side to the process area via the light path 9a to the diaphragm pressure converter 23 and back. From the signal receiving unit 32, the light signal via an optical fiber 22, outside the plant chamber 30, to Fabry Perot - Signalausnce 24 which determines there the above-mentioned pressure measurement signal and makes available, as shown in Figures 2 to 4.
• the thickness of the membrane together with its free diameter and the desired maximum bend thus define the pressure range to be used.
• the pressure measuring cell arrangement is shown with the signal receiving unit 32 and the membrane pressure converter 23, as provided in a process plant according to the invention, with appropriate separation 25 of the process space 12, 34 with respect to the plant chamber 30.
• a process is carried out as usual, preferably a vacuum process.
• the plant chamber 30 forms the general separation between process atmosphere 12 and ambient Atmosphere 10 according to the normal atmosphere (ambient). These two areas can also be referred to as different climatic chambers, since a different climate or different conditions prevail in the process space 12, such as pressure, gas types, processes, charge carriers, etc.
• the present invention makes it possible to selectively measure pressures at desired defined locations, in particular within process spaces 34, by positioning the membrane pressure transducer 23 close to this location.
• this location exists between this location and the plant chamber wall 30, either a natural separation region 25, formed by release agent 25, by the formation of the process configuration itself or specially arranged release means 25.
• Between the release agent 25 and the plant chamber wall 30 thereby forms a separate air conditioning chamber 11, 33 which acts separating or decoupling.
• Separating agent 25 may be measures that form, for example, simply pressure stages (pressure gradients), as known and customary in vacuum technology, magnetic and / or electrical fields such as for processes with charge carriers and / or mechanical means.
• a release agent 25 is shown, which is formed mechanically and sieve-like.
• a separation window 25a is provided on the separation means 25 for the passage of the light beam 9 for communicative communication between the diaphragm pressure transducer 23 and the signal acquisition unit 32.
• the partition window 25a is simply a hole 25a of the screen.
• the release agent 25 is shown as a wall 25, 31 and in this case, an optical separation window 25a, possibly sealingly connected to the wall must be provided for the passage of the light beam 9 in the light path region 9a for the passage of light.
• the wall can be part of a component of the process arrangement as needed and / or be formed as a separate component and have any shape. However, in particular suitably shaped sheet metal parts or even further walls of chambers are suitable.
• the membrane pressure transducer 23 is shown immersed in the process atmosphere in the examples of FIGS. 2a and 2b. However, it can also be directly part of such a separating means 25 and be incorporated therein at least partially sealing, as shown for example in Figures 3 and 4. In this case, no additional separation window 25a in the associated release agent 25 is necessary.
• the separating means 25, 31 may be formed with partial expansion or the inner space, in particular the process space 12, 34 also completely enclose.
• the partition wall 25, 31 may also at least partially have openings, but preferably it has no openings and is gas-tight.
• the signal receiving unit 32 is sealingly disposed in the plant chamber wall 30 which forms the periphery to the atmosphere 10. This in turn is connected on the atmosphere side 10 via a light guide, an optical fiber 22, with a signal evaluation unit 24.
• the signal evaluation unit 32 can be positioned, for example, as an attachment with a flange 20 on the plant chamber wall 30 and sealed there. It is also for example a holding device 21 is provided, which exactly fixes and aligns the optical fiber 22 and the LichtzuSciencean ever.
• At least one of the signal recording units 32-32 "contains light-focusing means in order to be able to align and focus the light beam 9 in a more precise and defined manner on the associated membrane pressure transducer 23, in particular its window 3 and the membrane 5.
• spherical lenses can be used or other lenses or lens systems are provided, which are arranged at the end of the optical fiber 22, in the direction of the diaphragm pressure converter 23 in the light path 9a.
• the distance between the surface of the housing body 1 of the membrane pressure transducer 23 in the region of the optical window 3 and the signal recording unit 32 may be in the range of 0.1 mm to 50 centimeters, preferably in the range of 1.0 mm to 100.0 mm. It should be noted that the housing body 1 and the signal receiving unit 32 are arranged correspondingly accurate and not tilted to each other, so that the optical path 9a with the light beam 9 at the surface of the window 3 on the housing body at an angle of 90 ° at a maximum deviation of ⁇ 100 mrad.
• FIG. 3 shows, by way of example, a process plant with a plant chamber 30 which completely encloses a process chamber 31 and thereby forms a climatic chamber 33, 11 separated from the process by the two chambers.
• this climatic chamber 33, 11 is evacuated with a vacuum pump 35 and the process gas is admitted from the process gas source 36 into the process chamber 34 into the process chamber 31 via a valve 37, for example for a plasma process.
• a heating arrangement 38 heated.
• the diaphragm pressure converter 23 is arranged integrated in the wall 31 of the process chamber.
• this can also be positioned further immersed in the process chamber 31, wherein then, as mentioned above, in the process chamber wall 31 in the region of the light path 9a, a separation window 25a is provided, which is the optical connection of the diaphragm pressure transducer 23 with the disposed on the outer chamber wall 30 Signalure - unit allows. It is also possible in the intermediate chamber to provide the air-conditioning chamber corresponding diaphragm pressure converter 23 and operate there even more separate processes and lead.
• process plant with a plant chamber 30 which completely encloses a plurality of process chambers 31-31 "which are nested one inside the other
• process chambers 31-31 which are nested one inside the other
• the separation means 25 also constitute different climate chambers 33, 34.
• process chambers can also be arranged side by side or in a mixed arrangement within the installation chamber 30.
• membrane pressure transducers 23-23 are arranged in each of the chamber walls.
• At least two process spaces 12, 34, 34 'are provided and in at least one of these process spaces at least one diaphragm pressure converter 23, wherein for each measuring cell 23, an associated mutually aligned signal receiving unit 32, 32' is assigned to the chamber wall 30, respectively an optical path 9, 9 'are in operative connection with each other.
• at least two process spaces 12, 34, 34 'are nested inside one another and are arranged separately via separating means 25, 31, 31' within the surrounding air conditioning space 33, wherein the separating means 25, 31, 31 'are preferably formed as walls, surround the process spaces and separate them.
• at least the climatic chamber 11, 33 is connected to a pump 35, preferably with a vacuum pump 35.
• a pressure measuring cell arrangement of the aforementioned type comprises the following steps:
• an optical membrane pressure transducer 23 which contains a housing body 1 containing at least one of a metal oxide, SiO 2 or SiC of metal oxide with a membrane 5 arranged at a small distance in the edge area, so that a reference pressure space 8 is formed therebetween , and that this membrane 5 is exposed to a process space 12, 34 with the gaseous medium to be measured, wherein an optically transparent window 3 is provided on the housing body 1 at least in the center region, the surface of which is formed partially reflecting on the side to the reference pressure space 8 and this facing surface of the diaphragm 5 is formed optically reflective at least in the center region, - arrangement of a signal receiving unit 32 with an optical fiber 22 for

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• 2009
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