Microfabricated Beam Modulation Device

Abstract

A beam modulation device gate is constructed from a silicon material, such as a silicon layer on an silicon on insulator wafer. The device further comprises a set of electrical contacts on the layer. The layer defines a set of electrically conducting silicon material fingers forming an array, wherein each of at least some of the fingers is connected electrically to one of the electrical contacts. The gate may be used in a mass or ion mobility spectrometer. Where the gate is constructed from a silicon on insulator wafer, an insulator layer supports the silicon layer and a handle layer supports the insulator layer. When predetermined electrical potentials are applied to the electrical contacts, at least some of the fingers will be substantially at said predetermined electrical potentials to modulate a beam of charged particles that passes through said array of fingers. A plurality of devices of the type above may be used, where each of the devices modulates the beam so that the beam is deflected along a direction different from direction along which the beam is deflected by any of the remaining devices. A plurality of devices of the type above may be used for a mass gate or charged particle buncher device. For making an ion optical device, an array of fingers is formed in a silicon layer of the silicon on insulator wafer. A portion of a handle layer of the wafer on a side of an insulator layer of the wafer opposite to that of the fingers is removed; and a portion of the insulator layer is removed so that the fingers are connected to the wafer only through the silicon layer and at one end of the fingers.

1 . An apparatus for electrically modulating a beam of charged particles, comprising: 
 a layer of silicon material;    a set of electrical contacts on the layer, said layer defining a set of electrically conducting silicon material fingers forming an array, wherein each of at least some of the fingers is connected electrically to one of the electrical contacts;    an insulator layer supporting said silicon layer; and    a handle layer supporting said insulator layer, so that when predetermined electrical potentials are applied to the electrical contacts, the at least some of the fingers will be substantially at said predetermined electrical potentials to modulate a beam of charged particles that passes through said array of fingers.    
   
   
       2 . The apparatus of  claim 1 , wherein each of said at least some of the fingers is individually addressable electrically separately from other fingers.  
   
   
       3 . The apparatus of  claim 1 , said set of contacts including a first and a second contact, wherein said set of silicon material fingers comprises a frame portion and a first and a second array of electrically conducting fingers, the fingers of the two arrays being connected to the frame portion on opposite sides of the frame portion, the fingers in the first array being electrically connected to the first electrical contact and the fingers in the second array being electrically connected to the second electrical contact.  
   
   
       4 . The apparatus of  claim 3 , wherein each pair of fingers in the first array being separated by at least one finger in the second array.  
   
   
       5 . The apparatus of  claim 1 , further comprising a layer of metallic material on said fingers.  
   
   
       6 . The apparatus of  claim 1 , wherein adjacent fingers in the sets are spaced apart by less than about 0.1 mm and are in the range of 1 mm to 10 mm in length.  
   
   
       7 . A mass spectrometer, comprising: 
 a layer of silicon material; and    a set of electrical contacts on the layer, said layer defining a set of electrically conducting silicon material fingers forming an array, wherein each of at least some of the fingers is connected electrically to one of the electrical contacts.    
   
   
       8 . The spectrometer of  claim 7 , wherein each of said at least some of the fingers is individually addressable electrically separately from other fingers.  
   
   
       9 . The spectrometer of  claim 7 , said set of contacts including a first and a second contact, wherein said set of silicon material fingers comprises a frame portion and a first and a second array of electrically conducting fingers, the fingers of the two arrays being connected to the frame portion on opposite sides of the frame portion, the fingers in the first array being electrically connected to the first electrical contact and the fingers in the second array being electrically connected to the second electrical contact.  
   
   
       10 . The spectrometer of  claim 9 , wherein each pair of fingers in the first array being separated by at least one finger in the second array.  
   
   
       11 . The spectrometer of  claim 7 , further comprising a layer of metallic material on said fingers.  
   
   
       12 . The spectrometer of  claim 7 , wherein adjacent fingers in the sets are spaced apart by less than about 0.1 mm and are in the range of 1 mm to 10 mm in length.  
   
   
       13 . The spectrometer of  claim 7 , further comprising: 
 an insulator layer supporting said silicon layer; and    a handle layer supporting said insulator layer, so that when predetermined electrical potentials are applied to the electrical contacts, the at least some of the fingers will be substantially at said predetermined electrical potentials to modulate a beam of charged particles that passes through said array of fingers.    
   
   
       14 . An apparatus for electrically modulating a beam of charged particles, comprising a plurality of devices, wherein each of the device modulates the beam so that the beam is deflected along a direction different from direction along which the beam is deflected by any of the remaining devices, wherein each of said plurality of devices comprises: 
 a layer of silicon material; and    a set of electrical contacts on the layer, said layer defining a set of electrically conducting silicon material fingers forming an array, wherein each of at least some of the fingers is connected electrically to one of the electrical contacts.    
   
   
       15 . The apparatus of  claim 14 , wherein two of said plurality of devices deflect the beam in perpendicular directions.  
   
   
       16 . The apparatus of  claim 1 , wherein the fingers in said two of said plurality of devices are substantially perpendicular to one another.  
   
   
       17 . An apparatus for electrically modulating a beam of charged particles, comprising a plurality of devices, wherein each of said plurality of devices comprises: 
 a layer of silicon material;    a set of electrical contacts on the layer, said layer defining a set of electrically conducting silicon material fingers forming an array, wherein each of at least some of the fingers is connected electrically to one of the electrical contacts; and    a circuit that applies electrical potentials to the electrical contacts in the plurality of devices so that bunches of particles pass intermittently through the plurality of devices.    
   
   
       18 . A method for making an ion optical device, comprising: 
 providing a silicon on insulator wafer;    forming an array of fingers in a silicon layer of the wafer;    removing a portion of a handle layer of the wafer on a side of an insulator layer of the wafer opposite to that of the fingers; and    removing a portion of the insulator layer so that the fingers are connected to the wafer only through the silicon layer and at one end of the fingers.    
   
   
       19 . The method of  claim 18 , further comprising forming a layer of metal on the silicon layer prior to the formation of the array of fingers.  
   
   
       20 . The method of  claim 18 , wherein said forming of the array of fingers and the removing of portions of the handle and insulator layers comprise etching.  
   
   
       21 . The method of  claim 18 , further comprising protecting said fingers when said portion of the handle layer is removed.  
   
   
       22 . An ion mobility spectrometer, comprising: 
 a layer of silicon material; and    a set of electrical contacts on the layer, said layer defining a set of electrically conducting silicon material fingers forming an array, wherein each of at least some of the fingers is connected electrically to one of the electrical contacts.    
   
   
       23 . The ion mobility spectrometer of  claim 22 , wherein each of said at least some of the fingers is individually addressable electrically separately from other fingers.  
   
   
       24 . The ion mobility spectrometer of  claim 22 , said set of contacts including a first and a second contact, wherein said set of silicon material fingers comprises a frame portion and a first and a second array of electrically conducting fingers, the fingers of the two arrays being connected to the frame portion on opposite sides of the frame portion, the fingers in the first array being electrically connected to the first electrical contact and the fingers in the second array being electrically connected to the second electrical contact.  
   
   
       25 . The spectrometer of  claim 24 , wherein each pair of fingers in the first array being separated by at least one finger in the second array.  
   
   
       26 . The spectrometer of  claim 22 , further comprising a layer of metallic material on said fingers.  
   
   
       27 . The ion mobility spectrometer of  claim 22 , wherein adjacent fingers in the sets are spaced apart by less than about 0.1 mm and are in the range of 1 mm to 10 mm in length.  
   
   
       28 . The ion mobility spectrometer of  claim 22 , further comprising: 
 an insulator layer supporting said silicon layer; and    a handle layer supporting said insulator layer, so that when predetermined electrical potentials are applied to the electrical contacts, the at least some of the fingers will be substantially at said predetermined electrical potentials to modulate a beam of charged particles that passes through said array of fingers.