Electrically tunable fabry-perot interferometer, an intermediate product an electrode arrangement and a method for producing an electrically tunable fabry-perot interferometer

Abstract

Electrically tunable Fabry-Perot interferometers which are produced with micromechanical (MEMS) technology. Producing interferometers with prior art processes includes costly and complicated production phases. Therefore, it has not been possible to apply interferometers in consumer mass products. According to the present solution, the Fabry-Perot cavity is made by removing a sacrificial layer ( 112 ) which has been polymer material. A mirror layer ( 113, 117 - 120 ) which is produced above the sacrificial layer can be made with atomic layer deposition technology, for example. According to a preferable embodiment, electrodes ( 106 b, 115 b ) of the mirror structures are formed by using sputtering or evaporation. With the present solution it is possible to avoid the above mentioned problems related with prior art.

1 - 44 . (canceled) 
     
     
         45 . Method for producing an electrically tunable Fabry-Perot interferometer, wherein
 a substrate is provided,   a first mirror structure is provided on the substrate,   a second, movable mirror structure is provided, whereby the first and second mirror structures comprise first and second mirrors which are substantially parallel,   a Fabry-Perot cavity is provided between the first and second mirrors, whereby providing the cavity comprises providing a sacrificial layer on the first mirror structure, and at least part of the sacrificial layer is removed after providing the second mirror structure,   providing electrodes for electrical control of the distance between the mirrors,   
       wherein polymer material is applied as the sacrificial layer, and an electrically semi-insulating layer is provided in the mirror structure. 
     
     
         46 . Method according to  claim 45 , wherein providing the second, movable mirror structure comprises providing at least one layer with a process wherein the temperature of the sacrificial layer remains below the glass transition temperature of the polymer material. 
     
     
         47 . Method according to  claim 45 , wherein the substrate is a wafer on which several interferometer chips are formed, whereby the interferometer chip is cut out from the wafer. 
     
     
         48 . Method according to  claim 47 , characterised in that the at least part of the sacrificial layer is removed after the interferometer chip has been cut out from the wafer. 
     
     
         49 . Method according to  claim 45 , wherein an interferometer chip is encapsulated, and the at least part of the sacrificial layer is removed after encapsulating of the interferometer chip. 
     
     
         50 . Method according to  claim 45 , wherein through-holes are provided into the second, movable mirror structure, and the at least part of the sacrificial layer of polymer material is removed via the through-holes. 
     
     
         51 . Method according to  claim 45 , wherein the at least part of the sacrificial layer is removed by dry etching. 
     
     
         52 . Method according to  claim 51 , wherein the at least part of the sacrificial layer is removed by applying oxygen plasma. 
     
     
         53 . Method according to  claim 45 , wherein a support for the second movable mirror is provided by remaining polymer at the edges of the initially formed polymer layer. 
     
     
         54 . Method according to  claim 45 , wherein providing the second, movable mirror structure comprises providing at least one optical layer by using atomic layer deposition. 
     
     
         55 . Method according to  claim 45 , wherein providing the electrodes comprises sputtering or evaporating a thin film of electrically conductive material. 
     
     
         56 . Method according to  claim 45 , wherein an electrically insulating or semi-insulating layer is provided on the surface the electrode layer, between the electrode layer and the Fabry-Perot cavity, for protecting the electrode layer. 
     
     
         57 . Method according to  claim 45 , wherein an electrically semi-insulating layer is provided in the optical area of the mirror for preventing occurrence of charging. 
     
     
         58 . Method according to  claim 45 , wherein at least one of the electrodes is electrically floating. 
     
     
         59 . Method according to  claim 45 , wherein a radiation detector is integrated on the same substrate ( 230 ) with the interferometer for the measurement of the radiation which penetrates through the interferometer. 
     
     
         60 . Electrically tunable Fabry-Perot interferometer, comprising
 a substrate,   a first mirror structure on the substrate,   a second, movable mirror structure, whereby the first and second mirror structures comprise first and second mirrors which are substantially parallel,   a Fabry-Perot cavity between the first and second mirrors, whereby the cavity has been formed by providing a sacrificial layer on the first mirror structure, and at least partially removing the sacrificial layer after providing the second mirror structure,   electrodes for electrical control of the distance between the mirrors,   
       wherein the cavity has been made with sacrificial layer comprising polymer material, and the mirror structure comprises an electrically semi-insulating layer. 
     
     
         61 . Electrically tunable Fabry-Perot interferometer according to  claim 60 , wherein the second, movable mirror structure comprises at least one layer which has been deposited in an environment wherein the temperature of the sacrificial layer remains below the glass transition temperature of the polymer material. 
     
     
         62 . Electrically tunable Fabry-Perot interferometer according to  claim 60 , wherein the second, movable mirror structure includes through-holes for releasing the second, movable mirror structure by removing the polymer material through said through-holes. 
     
     
         63 . Electrically tunable Fabry-Perot interferometer according to  claim 60 , wherein the interferometer comprises an interferometer chip which has been cut out from a wafer. 
     
     
         64 . Electrically tunable Fabry-Perot interferometer according to  claim 63 , wherein the at least part of the sacrificial layer has been removed after the interferometer chip has been cut out from the wafer. 
     
     
         65 . Electrically tunable Fabry-Perot interferometer according to  claim 60 , wherein the interferometer comprises a package and an interferometer chip, whereby the at least part of the sacrificial layer has been removed when the interferometer chip has been inside the packaging. 
     
     
         66 . Electrically tunable Fabry-Perot interferometer according to  claim 60 , wherein the at least part of the sacrificial layer has been removed by dry etching. 
     
     
         67 . Electrically tunable Fabry-Perot interferometer according to  claim 66 , wherein the at least part of the sacrificial layer has been removed by applying oxygen plasma. 
     
     
         68 . Electrically tunable Fabry-Perot interferometer according to  claim 60 , wherein it comprises a support for the second, movable mirror at the edge area of the second movable mirror. 
     
     
         69 . Electrically tunable Fabry-Perot interferometer according to  claim 68 , wherein the support is a polymer layer between the layers of the first and second mirror layers, at the edges of the cavity of the interferometer. 
     
     
         70 . Electrically tunable Fabry-Perot interferometer according to  claim 60 , wherein the second mirror structure comprises at least one optical layer formed by atomic layer deposition. 
     
     
         71 . Electrically tunable Fabry-Perot interferometer according to  claim 60 , wherein at least one of the electrodes are formed by sputtering or evaporating a thin film of electrically conductive material. 
     
     
         72 . Electrically tunable Fabry-Perot interferometer according to  claim 60 , wherein it comprises an electrically insulating or semi-insulating layer on the surface the electrode layer, between the electrode layer and the Fabry-Perot cavity, for protecting the electrode layer. 
     
     
         73 . Electrically tunable Fabry-Perot interferometer according to  claim 60 , wherein it comprises an electrically semi-insulating layer in the optical area of the mirror for preventing occurrence of charging. 
     
     
         74 . Electrically tunable Fabry-Perot interferometer according to  claim 60 , wherein one of the electrodes is electrically floating. 
     
     
         75 . Electrically tunable Fabry-Perot interferometer according to  claim 60 , wherein the interferometer is integrated with a radiation detector for the measurement of the radiation which penetrates through the interferometer. 
     
     
         76 . Intermediate product of an electrically tunable Fabry-Perot interferometer, comprising
 a substrate,   a first mirror structure on the substrate,   a second, movable mirror structure, whereby the first and second mirror structures comprise first and second mirrors which are substantially parallel,   a sacrificial layer between the first and second mirror structures,   electrodes for electrical control of the distance between the mirrors,   
       characterised in that the sacrificial layer includes polymer material, and the mirror structure comprises an electrically semi-insulating layer. 
     
     
         77 . Intermediate product according to  claim 76 , wherein the second, movable mirror structure comprises at least one layer which has been deposited in an environment wherein the temperature is below the glass transition temperature of the polymer material. 
     
     
         78 . Intermediate product according to  claim 76 , wherein the second, movable mirror structure includes through-holes for releasing the second, movable mirror structure by removing the polymer material through said through-holes. 
     
     
         79 . Intermediate product according to  claim 76 , wherein the second mirror structure comprises at least one optical layer formed by atomic layer deposition. 
     
     
         80 . Intermediate product according to  claim 76 , wherein at least one of the electrodes has been formed by sputtering or evaporating a thin film of electrically conductive material. 
     
     
         81 . Intermediate product according to  claim 76 , wherein it comprises an electrically insulating or semi-insulating layer on the surface the electrode layer, between the electrode layer and the sacrificial layer, for protecting the electrode layer. 
     
     
         82 . Intermediate product according to  claim 76 , wherein it comprises an electrically semi-insulating layer in the optical area of the mirror for preventing occurrence of charging. 
     
     
         83 . Intermediate product according to  claim 76 , wherein one of the electrodes is electrically floating. 
     
     
         84 . Intermediate product according to  claim 76 , wherein the intermediate product comprises a chip which has been is cut out from a wafer. 
     
     
         85 . Intermediate product according to  claim 76 , wherein the intermediate product comprises an enclosure, and a chip in the enclosure. 
     
     
         86 . Intermediate product according to  claim 76 , wherein the intermediate product is integrated with a radiation detector. 
     
     
         87 . Electrode arrangement in a micromechanical component, which has a first part and a second part, in which component there is a first electrode in the first part and a second electrode in the second part, and wherein distance between the first part and the second part is controlled by applying a voltage between the first and second electrodes, said first and second electrodes forming a first capacitance, wherein there is a third electrode in the first part, wherein there is a second capacitance between the second and third electrodes, whereby the first and second capacitances are series connected, and the AC voltage applied between the first and third electrodes is adapted to form a control voltage across the first capacitance for controlling the distance between the first and second parts. 
     
     
         88 . Electrode arrangement according to  claim 87 , wherein the micromechanical component is an electrically tunable Fabry-Perot interferometer, whereby the first part comprises a first mirror and the second part comprises a second mirror of the Fabry-Perot interferometer, and the distance between the first and second mirrors is controllable.