Apparatus comprising a rotating contaminant trap

Abstract

A contaminant trap apparatus arranged in a path of a radiation beam to trap contaminants emanating from a radiation source configured to produce the radiation beam is disclosed. The contaminant trap apparatus includes a rotor having a plurality of channel forming elements defining channels which are arranged substantially parallel to the direction of propagation of the radiation beam, the rotor including electrically chargeable material and arranged to be electrically charged as a result of the operation of the radiation source; and a bearing configured to rotatably hold the rotor with respect to a rotor carrying structure, wherein the apparatus is configured to (i) control or redirect an electrical discharge of the rotor, or (ii) suppress an electrical discharge of the rotor, or (iii) both (i) and (ii).

1 .- 20 . (canceled) 
     
     
         21 . A method, comprising:
 trapping contaminants emanating from a radiation source using a rotor, the rotor having a plurality of channel forming elements defining channels arranged substantially parallel to a direction of propagation of a radiation beam emitted from the radiation source, the rotor comprising electrically chargeable material that becomes electrically charged as a result of the operation of the radiation source; and   controlling or redirecting an electrical discharge of the rotor, or suppressing an electrical discharge of the rotor, or both.   
     
     
         22 . The method according to  claim 21 , comprising controlling the electrical discharge of the rotor by using an electrically conductive coupling in electrical contact with an electrically conductive part of the rotor and in electrical contact with an electrically conductive part of a rotor carrying structure, a charge drain, or both. 
     
     
         23 . The method according to  claim 21 , comprising bearing the rotor using a fluid bearing structure and wherein a part of the rotor comprises electrically insulating material to prevent flow of electrical charge, at the fluid bearing structure, between the rotor and a bearing surface of the fluid bearing structure. 
     
     
         24 . The method according to  claim 21 , comprising bearing the rotor using a fluid bearing structure, supplying a bearing fluid or fluid mixture to between a first part of the rotor and the fluid bearing structure using the fluid bearing structure, and stimulating an electrical discharge with the rotor in an area outside the fluid bearing structure using (i) a discharge stimulating structure, or (ii) a discharge stimulating fluid or fluid mixture, or (iii) both (i) and (ii), at or near a different second part of the rotor, the second part being attached to the rotor and exchanging charge with the electrically chargeable material. 
     
     
         25 . The method according to  claim 24 , wherein the second part is not substantially surrounded by the fluid bearing structure and extends between the channel elements and the first part. 
     
     
         26 . The method according to  claim 24 , wherein the discharge stimulating fluid or fluid mixture has a lower breakdown voltage than the bearing fluid or fluid mixture. 
     
     
         27 . The method according to  claim 24 , wherein the discharge stimulating structure comprises an electrically conductive electrode, extending or reaching to a location near an outer surface of the second part, the electrode being connected to a charge drain or a potential source. 
     
     
         28 . The method according to  claim 21 , comprising bearing the rotor using a fluid bearing structure and supplying an electrically conducting fluid or fluid mixture using the fluid bearing structure to provide an electrical conducting path between the rotor and a rotor carrying structure. 
     
     
         29 . The method according to  claim 21 , comprising bearing the rotor using a fluid bearing structure, and wherein the channel forming elements comprise plates defining the channels, the plates arranged substantially parallel to the direction of propagation of the radiation beam, and wherein a part of the rotor reaches into the fluid bearing structure. 
     
     
         30 . The method according to  claim 21 , further comprising patterning the radiation beam and projecting the patterned radiation beam onto a radiation-sensitive substrate. 
     
     
         31 . An apparatus comprising:
 a carrying structure; and   a contaminant trapping structure, supported by the carrying structure, to trap contaminants emanating from a radiation source, the contaminant trapping structure being movable with respect to the carrying structure and defining a plurality of channels which are arranged, in use, in a path of propagation of a radiation beam from the radiation source, the contaminant trapping structure comprising electrically chargeable material and arranged to be electrically charged as a result of the operation of the radiation source,   wherein the apparatus is configured to (i) control or redirect an electrical discharge of the contaminant trapping structure, or (ii) suppress an electrical discharge of the contaminant trapping structure, or (iii) both (i) and (ii).   
     
     
         32 . The apparatus according to  claim 31 , wherein electrical discharge of the contaminant trapping structure is controlled by an electrically conductive coupling, which is in electrical contact with an electrically conductive part of the contaminant trapping structure and with an electrically conductive part of the carrying structure, a charge drain, or both. 
     
     
         33 . The apparatus according to  claim 31 , further comprising a fluid bearing structure, provided between a part of the contaminant trapping structure and a part of the carrying structure, wherein the fluid bearing structure is configured to supply an electrically conducting fluid or fluid mixture to provide an electrical conducting path between the contaminant trapping structure and the carrying structure. 
     
     
         34 . The apparatus according to  claim 31 , further comprising a fluid bearing structure, provided between a part of the contaminant trapping structure and a part of the carrying structure, wherein the contaminant trapping structure comprises electrically insulating material to prevent flow of electrical charge, at the fluid bearing structure, between the contaminant trapping structure and a bearing surface of the carrying structure. 
     
     
         35 . The apparatus according to  claim 31 , further comprising a fluid bearing structure, provided between a first part of the contaminant trapping structure and a part of the carrying structure, wherein the fluid bearing structure is configured to supply a fluid or fluid mixture to between the first part of the contaminant trapping structure and the carrying structure, and wherein (i) a discharge stimulating structure is provided, or (ii) a discharge stimulating fluid or fluid mixture is configured to be provided, or (iii) both (i) and (ii), at or near a different second part of the contaminant trapping structure to stimulate an electrical discharge with the contaminant trapping structure in an area outside the fluid bearing structure, the second part being attached to the contaminant trapping structure and being able to exchange charge with the electrically chargeable material. 
     
     
         36 . The apparatus according to  claim 31 , further comprising a substrate table configured to hold a substrate, and a projection system configured to project the radiation beam as patterned onto the substrate. 
     
     
         37 . A method, comprising:
 trapping contaminants emanating from a radiation source using a moveable contaminant structure defining a plurality of channels arranged in a path of propagation of a radiation beam emitted from the radiation source, the contaminant structure comprising electrically chargeable material that becomes electrically charged as a result of the operation of the radiation source; and   controlling or redirecting an electrical discharge of the contaminant structure, or suppressing an electrical discharge of the contaminant structure, or both.   
     
     
         38 . The method according to  claim 37 , comprising controlling the electrical discharge of the contaminant structure by using an electrically conductive coupling in electrical contact with an electrically conductive part of the contaminant structure and in electrical contact with an electrically conductive part of the carrying structure, a charge drain, or both. 
     
     
         39 . The method according to  claim 37 , comprising bearing the contaminant structure using a fluid bearing structure and wherein a part of the contaminant structure comprises electrically insulating material to prevent flow of electrical charge, at the fluid bearing structure, between the contaminant structure and a bearing surface of the fluid bearing structure. 
     
     
         40 . The method according to  claim 37 , comprising bearing the contaminant structure using a fluid bearing structure, supplying a bearing fluid or fluid mixture to between a first part of the contaminant structure and the fluid bearing structure using the fluid bearing structure, and stimulating an electrical discharge with the contaminant structure in an area outside the fluid bearing structure using (i) a discharge stimulating structure, or (ii) a discharge stimulating fluid or fluid mixture, or (iii) both (i) and (ii), at or near a different second part of the contaminant structure, the second part being attached to the contaminant structure and exchanging charge with the electrically chargeable material. 
     
     
         41 . The method according to  claim 37 , comprising bearing the contaminant structure using a fluid bearing structure and supplying an electrically conducting fluid or fluid mixture using the fluid bearing structure to provide an electrical conducting path between the contaminant structure and a structure carrying the contaminant structure.