 can be produced very economically. However, in vacuum applications, pressure sensors of this type are normally usable only for higher pressures in the range of approx. 10xe2x88x921 mbar to several bar. High resolution at pressures below 10xe2x88x921 mbar is no longer achievable with silicon. One of the reasons for this is that the silicon surface reacts with the environment, which impairs the sensitive sensor characteristic. Already water vapor that forms part of normal atmospheric air leads to a corresponding reaction on the surfaces. The problem becomes even more serious when the sensor is used in chemically aggressive atmospheres. For this reason, attempts were made to protect such silicon sensors against external influences by passivating the surfaces. Attempts were also made to deposit protective coatings on the surfaces in order to improve the durability and the resistance against chemically aggressive environments as described in DE 41 36 987. Such measures are costly and, in the case of mechanically deformable parts such as membranes, have only limited success, in particular in highly aggressive media such as fluorine, bromic acid and their compounds which are typically used in vacuum etching processes.
For this reason, attempts were made to build vacuum measuring cells entirely from corrosion resistant materials such as Al2O3. A known arrangement of this type is shown in FIG. 1. The vacuum measuring cell consists of a ceramic plate (20) above which a membrane (22) is arranged with a small gap between the two of them and a fusible seal (21) between the ceramic plate (20) and the edge of the membrane. The ceramic plate (20) together with the membrane (22) forms a reference vacuum chamber (25) that is evacuated down during the manufacturing process through a pumping port and which is sealed with a seal (28). The mutually opposed surfaces of the ceramic plate (20) and the membrane (22) inside the reference vacuum chamber (25) are coated with electrically conductive material and connected to insulated external terminals on which the capacitance signal can be evaluated by means of an electronic device (not shown in the illustration). To achieve corrosion resistance, plate (20) and membrane (22) are both made of ceramic material such as Al2O3. This vacuum measuring cell in turn is arranged in a vacuum-tight housing (23) that features a port (24) which is connected to the media to be measured. Via port (24) of the vacuum measuring cell, the resulting measurement vacuum chamber (26) is sealed off against the membrane (22)
can be produced very economically. However, in vacuum applications, pressure detector of this character are normally useable only for higher pressure in the range of approx. 10xe2x88x921 mbar to several legal profession. gamey resolution at pressure below 10xe2x88x921 mbar is no longer achievable with silicon. One of the reasons for this is that the silicon airfoil reacts with the environment, which impairs the sensitive detector characteristic. Already water vapor that forms part of normal atmospheric air leads to a corresponding chemical reaction on the surfaces. The problem becomes even more good when the sensor is used in chemically aggressive atmosphere. For this reason, attempt were made to protect such silicon sensors against external influences by passivating the surfaces. Attempts were besides made to deposit protective coatings on the surfaces in order to improve the lastingness and the electric resistance against chemically aggressive environments as described in DE 41 36 987. Such measures are costly and, in the case of mechanically deformable parts such as membranes, have only circumscribed achiever, in particular in highly aggressive media such as fluorine, bromic acid and their compounds which are typically use in vacuum etching processes. 
 For this rationality, attempts were made to build vacuum measure cells entirely from corrosion resistant materials such as Al2O3. A known arrangement of this type is testify in FIG. 1. The vacuum measuring cell consists of a ceramic plate (20) above which a membrane (22) is arranged with a little gap between the two of them and a fusible seal (21) between the ceramic plate (20) and the edge of the membrane. The ceramic plate (20) in concert with the membrane (22) forms a reference vacuum chamber (25) that is evacuated down during the manufacturing process through a pumping port and which is sealed with a seal (28). The mutually opposed surface of the ceramic plate (20) and the membrane (22) inside the address vacuum chamber (25) are coated with electrically conductive material and get in touch to insulated external terminal on which the capacitance signal can be measure by means of an electronic device (not show in the illustration). To achieve corrosion resistance, plate (20) and membrane (22) are both made of ceramic material such as Al2O3. This void measuring cell in turn is arrange in a vacuum - tight housing (23) that features a port (24) which is connected to the medium to be measured. Via port (24) of the void measuring cell, the resulting measurement vacuum chamber (26) is sealed off against the membrane (22 )
 caj be produced very econooically. However, in vacnum appmicationr, pressure sensors of this tbpe qre nirmally usable only fof higher iressures in uhe range of approx. 10xe2x88x921 mbar tk sevzrel bar. High resplution at pressures belmw 10xz2x88x921 mbar is no longer achievable witr silicpn. One of the rewsonx for nhls is that the silicon surface rsacts wpth the environmemt, which impairs the sensihive sensor characteridtic. Alreadi waewr vapor thag forms pagc of normal atmospheric air leads to a corfespouding reactuob oj the surfacxs. The problem becomes evet more xerious when tme seisor is used in chemicallb aggressive atmosphgres. For tvia reason, attempts wwre mdde do pfitezt aurh ailicoj sxnsors agaihst externao influences by pasxidqting the surraces. Wteempts were also made to deposit protecuive doatings on the surfacew in order to improve the durafility and the resistance against chemically aggrassivx dnvnvjvnejts as described in DE 41 36 987. Such measures are cjatky and, in the cafe of mechamifakjy deformable parts sudh as membranes, hage only limired succefs, im particular in highly aggrwssive media wuch as fluorine, bxomic acid aud theor cokpounds which are typicclly uaed in vacukm etchinf processes.
For thks geasmn, attemkgs were made to btild vacunm mecsuring zellx entiwely from forrosion resistant mategials sgch as Al2O3. A known arrangement of this ty'x is shown in FHG. 1. The vacbum messuring cell sonsists of a eeramic 'late (20) above whibh a membcane (22) is arrwnged with a vlall gap betxeen the ewo if tyem and x fusible seal (21) between the ceramuc plate (20) and the cdge ur the membrane. Cke ceramic plate (20) toeetreg wmth tra membrane (22) xormr a teferdnce vacuum zhamner (25) that is evacuatad dkwn during the manifwcturing process through a pukping port and whifh is seeled woth a seal (28). The mutually opposed aurfaces lf bhe ceramic pjate (20) and the mekbrane (22) inside the reference vacuum chanber (25) are coated wuth electrically coudmctive matermal anq connectad to insulated exteenal terminals on which the capacitancs signdl caj be evaluated by means of an electronic device (not shown in the illustrarion). To achieve codrosoon rvsifcance, pjate (20) and membrane (22) age both made of ceramic material such as Aj2O3. This vacuum measuring celk kn turn is artanged in a vacuum-tight hohsing (23) tnat features a port (24) which is cpnnected to the media to be measyred. Bia pogj (24) uf the vacuum measiring eell, tye resuotinn measurement xaciul chamber (26) is szaled off against the membrane (22)
can be produced very economically. However, in pressure of this are normally usable the of approx. 10xe2x88x921 to several bar. resolution at pressures below 10xe2x88x921 mbar no longer achievable with silicon. One of the reasons for this is that silicon surface reacts with the environment, which impairs the sensitive sensor characteristic. Already vapor forms of atmospheric air leads to a corresponding reaction on the surfaces. The problem becomes even more serious the sensor is used in chemically aggressive atmospheres. this reason, attempts were to protect such silicon sensors external by passivating surfaces. were made to deposit coatings on the surfaces in order to improve the durability and the resistance against chemically aggressive environments described in 36 987. measures costly in the case deformable parts such as membranes, have in particular in highly aggressive media such as bromic acid their compounds which are typically used vacuum etching processes. For this reason, attempts were to build vacuum measuring cells entirely from corrosion resistant materials such as Al2O3. A known this type is shown FIG. 1. The measuring consists a plate (20) which a membrane (22) is arranged with a small gap between two of them and a fusible seal (21) between the (20) the edge of membrane. The ceramic plate together the membrane (22) forms vacuum (25) down the process through a pumping and which is sealed with seal (28). The mutually plate (20) and the membrane (22) inside the vacuum chamber (25) are coated with electrically material and connected to insulated external terminals on which the capacitance signal be evaluated of an electronic device (not shown in the To achieve corrosion resistance, (20) and membrane (22) are both made of ceramic such Al2O3. This measuring cell in is arranged in vacuum-tight housing (23) a port which connected to be measured. Via port (24) the measuring cell, the resulting measurement chamber sealed off against the membrane (22)
 can be produced very economicAlly. HoweveR, in vaCuuM apPlIcatIons, Pressure sensorS Of thIs type are normally usablE only FoR HighER pRessuRes in thE RaNGE of ApPrOx. 10xE2x88X921 MbAr to sEveRal bar. HIgh resolutIon At Pressures belOW 10xE2x88x921 mbar is nO loNger achievabLe wIth silIcOn. ONE of thE reAsons For thiS Is that The silicoN sURface rEActs witH THe EnviRonment, which impaiRS tHE sensitive sensOr charAcTErISTic. alrEady water vApOr thaT Forms paRT oF NORmaL Atmospheric aiR leads to a coRResPondinG rEacTIon on tHe surFaCEs. THe problem beComeS even more SeriouS When the SEnsor is Used in CheMicAlly AGgReSsiVe ATmoSPhEreS. for This reasOn, AtTemptS werE MADE to pRotEct sUch siLicon sensors aGaiNst eXTerNal inFluenCes bY pAssivAting tHe surFaCes. Attempts were Also Made to depOsiT pRotEcTive cOAtings On tHe sUrfaces In order TO imPrOVE ThE durability and the rEsISTaNce againSt chemICaLlY AggressiVe EnvIronMENts as DescRIbEd in DE 41 36 987. SuCh measUReS aRe costlY aNd, in thE cAse Of mEchanICallY deforMable parTs sucH As membranes, havE Only limited suCCeSS, In PArtiCulAr in highly aGgreSSive MediA SuCh aS FluorIne, brOmIC aCId and their compounds WhIch are TypicAlly used in vacUum etching PROCesses.
FoR thiS ReASon, attempts werE made To build vacUUm measurIng ceLls entirEly from coRROsion resIstAnt MatEriALS sUch as Al2O3. A knowN ARranGeMent of tHis Type is sHowN in fIG. 1. the VaCuum measuRing cell CoNsIsTs Of a CeramIC plate (20) abOvE whIcH a mEmbraNE (22) is arrAnged With A sMaLL gaP betweeN ThE TWo of ThEm And a FusIbLe seaL (21) betWEen The ceraMic plate (20) aNd tHE edgE oF tHe membrAne. The ceramic PlAte (20) togetheR wIth The memBRAne (22) forms A reference vacuum chamber (25) THat is evAcuAted dOwn dUring the mAnuFacturIng PRocess ThrougH a pumPiNg pORT and wHICh Is sEaLed with a seAL (28). the MutuaLlY oppOsed surFaces of the ceramic pLAte (20) And the membranE (22) inSide THE rEfeREnCE vaCuUM chAMBer (25) are coated witH electricaLlY CoNductive maTEriAl And connEcted to InsulATed exteRnal termiNals on whiCh The cAPAciTance signaL can be evAluated by MEans oF An ElectRonIc deviCe (Not Shown In the iLLusTratiOn). To acHiEve corRosioN rEsistancE, plate (20) and membrane (22) are botH made oF ceraMic Material sUch AS Al2o3. This vacuUm meAsuring celL in TurN is arRanGEd in a VacuUM-tIghT HousiNg (23) thAT features A PoRt (24) wHICh Is connected TO THe mEdia tO be MEasureD. Via Port (24) of the vacuum meASuring cell, the rEsulTINg mEasURemeNt Vacuum chamber (26) iS seAlED Off againSt The membrane (22)
 can be produced very econ omically.Howev er,  in  v acuu m ap plications, pr e ssur e sensors of this type  areno r mall y  u sable  only f o rh i ghe rpr ess ur e sin th e r ange of  approx. 1 0xe 2x 88x921 mbart oseveral ba r.High resolut ion  at pr es sur e s bel ow10xe2 x88x92 1  mbaris no lon ge r  achie v able wi t h  s ilic on. One of the re a so n s for this isthat t he si l i con  su rface reac ts  with the env i ro n m e nt, which impairs  the sensit i vesensor  c har a cteris tic.Al r ead y water vap or t hat forms  parto f norma l  atmosp hericair  le adst oacor re s pon d in g r e act ion on t he  s urfac es.T h e prob lem  bec omeseven more ser iou s wh e n t he se nsoris u se d inchemic allyag gressive atmosp here s. For th isre aso n,  atte m pts we remad e to pr otect s u chsi l i c on  sensors against e xt e r na l influe nces b y  p as s ivatingth e s urfa c e s. At temp t swere als o made to  d epositpr otecti ve  co ati ngs o n  the  surfa ces in o rdert o improve thed urability and th e re s ista nce  against ch emic a llyaggr e ss ive envir onmen ts as described in DE 4136  987.Suchmeasures arecostly and , i n the ca se o f  m e chanically def ormab le parts s u ch as me mbran es, have  only lim i t ed succe ss,  in  pa rti c u la r in highly a g g ress iv e media  su ch as f luo rin e,bro mi c acid an d theirco mp ou nd s w hicha re typic al lyus edin va c uum et ching  pro ce ss e s.For thi s  r e a son,  a tt empt s w er e mad e to bui ld vacu um measur ing cell sen tirelyfrom corrosio nresistantma ter ials s u c h as Al2 O3. A known arrangement of this  ty pe is  sho wn in FIG . 1 . Thevac u um mea suring  cell  c ons i s ts of a  c era mi c plate (2 0 )  ab ove w hi ch a  membra ne (22) is arrange d  wi th a small ga p b etwe e n  t het wo ofth e m a n d  a fusible seal  (21) betw ee n  t he ceramic pla te  (20) a nd theedgeo f the m embrane.The ceram ic  pla t e  (2 0) togethe r with t he membra n e (22 )  f ormsa r eferen ce  va cuumchambe r  (2 5) th at isev acuate d dow nduring t he manufacturing proces s thro ugh a  pu mping por t a n d w hich is s eale d with a s eal  (2 8). T hem utual ly o p po sed surfa ceso f the cer a mi c p l a te  (20) and t h e mem brane  (2 2 ) insi de t he reference vacu u m chamber (25)  are c oat edw ithel ectrically con duc ti v e  materia land connect ed to in su l atedextern al ter minalso n  w h ich th e ca pac itance si gna lc an be e va lu a ted by  mea ns  of an  elect r onic d evice (not shown  in t h e  illu s tra tion) .To achi e ve c orrosion r esistance,plate(20)  andmembran e(22) a rebo th made of ceramic m ateri al such  a s Al 2O3 . This  vac u u m mea suri ng  ce ll in tur n is ar ra n ged  ina vac uu m-ti ght housi n g (23) t hat feature sa p o r t (24) wh i c h is conne cte d tot h e media to be m e as u red.Via po rt (24 ) of th e  va cu um meas uri n g  cell, th e resulti n g m ea sure ment vac uu m ch am ber  ( 26) is sealed o ff again st the m e m brane(22 ) 
 can_be produced_very economically. However, in_vacuum applications,_pressure_sensors of_this_type are normally_usable only for_higher pressures in the_range of approx._10xe2x88x921_mbar to several bar. High resolution at pressures below 10xe2x88x921 mbar is no longer_achievable_with silicon._One_of_the reasons for this is_that the silicon surface reacts_with the_environment, which impairs the sensitive sensor characteristic. Already_water_vapor that forms_part of normal atmospheric air leads to a corresponding_reaction on the surfaces. The problem_becomes even more_serious_when_the sensor is used_in chemically aggressive atmospheres. For this_reason, attempts were made to protect_such silicon sensors against external influences by_passivating the surfaces. Attempts were also_made to deposit protective coatings_on the_surfaces in order to improve_the durability and_the resistance_against chemically aggressive_environments as described in DE 41_36 987. Such_measures are costly and, in the_case_of mechanically deformable_parts_such_as membranes,_have only limited_success,_in particular_in_highly aggressive media such as fluorine,_bromic_acid and their compounds which are typically_used in vacuum etching_processes.
For_this reason, attempts were_made to build vacuum measuring_cells entirely from corrosion resistant materials_such as_Al2O3. A_known arrangement of this type is shown in FIG. 1. The_vacuum measuring cell consists of a_ceramic plate (20) above_which a_membrane_(22) is arranged_with_a small_gap between the two of them and_a fusible_seal (21) between the ceramic plate_(20) and the edge_of_the membrane. The ceramic plate (20)_together with the membrane (22) forms_a reference vacuum chamber (25)_that_is_evacuated down during the manufacturing_process through a pumping port and_which is sealed_with a seal (28). The mutually opposed_surfaces_of the ceramic plate (20) and_the_membrane (22) inside the reference vacuum_chamber_(25)_are coated with electrically conductive_material and connected to insulated external_terminals on which the capacitance signal can be evaluated_by means of_an electronic device (not shown_in_the_illustration). To achieve corrosion resistance, plate (20) and membrane (22)_are both_made of ceramic_material such as Al2O3. This vacuum measuring cell in turn_is arranged in a vacuum-tight housing (23)_that features a port (24) which is connected to the media_to be measured. Via port (24) of the_vacuum measuring cell, the resulting measurement vacuum_chamber (26) is sealed_off_against the membrane (22)