Apparatus for method for immersion lithography

Abstract

An apparatus for immersion lithography that includes an imaging lens which has a front surface, a fluid-containing wafer stage for supporting a wafer that has a top surface to be exposed positioned spaced-apart and juxtaposed to the front surface of the imaging lens, and a fluid that has a refractive index between about 1.0 and about 2.0 the fluid filling a gap formed in-between the front surface of the imaging lens and the top surface of the wafer. A method for immersion lithography can be carried out by flowing a fluid through a gap formed in-between the front surface of an imaging lens and a top surface of a wafer. The flow rate and temperature of the fluid can be controlled while particulate contaminants are filtered out by a filtering device.

1. An apparatus for immersion lithography comprising:
 an imaging lens having a front surface;   a wafer having a top surface to be exposed positioned spaced-apart and juxtaposed to said front surface of the imaging lens;   fluid retaining means for holding a fluid, said fluid having a refractive index between about 1.0 and about 2.0 filling a gap formed in-between said front surface of the imaging lens and said top surface of the wafer; and   cover means for said fluid-retaining means to protect said fluid around said imaging lens from particulates.   
     
     
       2. An apparatus for immersion lithography according to  claim 1  further comprising a wafer holding means for holding said wafer in place. 
     
     
       3. An apparatus for immersion lithography according to  claim 1  further comprising a fluid-retaining means for maintaining said fluid in said gap formed in-between said front surface of the imaging lens and said top surface of the wafer. 
     
     
       4. An apparatus for immersion lithography according to  claim 1  further comprising
 a wafer holding means for holding said wafer in place. 
 
     
     
       5. An apparatus for immersion lithography according to  claim 1 , wherein said apparatus is a device selected from the group consisting of a scan-and-repeat mask aligner, a step-and-repeat mask aligner and a proximity mask aligner. 
     
     
       6. An apparatus for immersion lithography according to  claim 3 , wherein said fluid-retaining means further comprises fluid circulating means for circulating said fluid through the gap formed in-between said front surface of the imaging lens and said top surface of the wafer. 
     
     
       7. An apparatus for immersion lithography according to  claim 3 , wherein said fluid-retaining means further comprises a temperature controlling means for controlling a temperature of said fluid. 
     
     
       8. An apparatus for immersion lithography according to  claim 3 , wherein said fluid-retaining means further comprises a fluid-filter means for substantially maintaining said fluid particle-free. 
     
     
       9. An apparatus for immersion lithography according to  claim 6 , wherein said fluid circulating means being a pump device. 
     
     
       10. An apparatus for immersion lithography according to  claim 1 , wherein said fluid-retaining means further comprises:
 a fluid inlet for replenish fluid in said fluid-retaining means; and   a fluid outlet for discharging fluid from said fluid-retaining means.   
     
     
       11. An apparatus for immersion lithography according to  claim 2 , wherein said wafer holding means being a vacuum means or a mechanical means. 
     
     
       12. An apparatus for immersion lithography according to  claim 2 , wherein said wafer holding means further comprises wafer-tilting means. 
     
     
       13. An apparatus for immersion lithography according to  claim 1  further comprising mirror means for monitoring a position of said imaging lens and said wafer. 
     
     
       14. A method for conducting immersion lithography comprising the steps of:
 providing an imaging lens having a front surface;   positioning a wafer having a top surface to be exposed spaced-apart and juxtaposed to said front surface of the imaging lens;   maintaining a fluid having a refractive index between about 1.0 and about 2.0 in a gap formed in-between said front surface of the imaging lens and said top surface of the wafer; and   moving said imaging lens in a longitudinal direction for focusing.   
     
     
       15. A method for conducting immersion lithography according to  claim 14  further comprising the step of moving said wafer in a lateral direction for repeated exposures. 
     
     
       16. A method for conducting immersion lithography according to  claim 14  further comprising the step of controlling a temperature of said fluid. 
     
     
       17. A method for conducting immersion lithography according to  claim 14  further comprising the step of submerging said wafer in the fluid. 
     
     
       18. A method for conducting immersion lithography so according to  claim 14  further comprising the step of controlling a flow of said fluid between said front surface of the imaging lens and said top surface of the wafer. 
     
     
       19. A method for conducting immersion lithography according to  claim 14  further comprising the step of filtering said fluid to substantially remove all particles. 
     
     
       20. An apparatus for immersion lithography comprising:
 an imaging lens having a front surface;   a moveable wafer stage means comprising a wafer holding means for holding a wafer in place, a fluid retaining means for retaining a fluid in the wafer stage means, a circulating means for circulating the fluid within the moveable wafer stage means, and a temperature controlling means for controlling the temperature of the fluid within the wafer stage means;   a wafer having a top surface to be exposed disposed upon the wafer holding means, the wafer top surface positioned apart from the imaging lens front surface of the imaging lens thereby forming a gap of less than 5 mm;   the fluid filling the gap; and   cover means for said fluid retaining means to protect said fluid disposed around said imaging lens from particulates.   
     
     
       21. An apparatus for immersion lithography according to claim 20 wherein the cover means seal the fluid from the atmospheric environment. 
     
     
       22. An apparatus for immersion lithography according to claim 20, further comprising tilting means for tilting and leveling the wafer. 
     
     
       23. An apparatus for immersion lithography according to claim 20, further comprising moving means for moving the wafer in a longitudinal direction for focusing and in the lateral direction for exposure of the wafer. 
     
     
       24. An apparatus for immersion lithography according to claim 20, wherein the wafer holding means comprises wafer-tilting means. 
     
     
       25. An apparatus for immersion lithography according to claim 20 further comprising a fluid retaining means for maintaining the fluid in the gap between the front surface of the imaging lens and the top surface of the wafer when the wafer is not completely submerged in the fluid. 
     
     
       26. An apparatus for immersion lithography according to claim 20, wherein the apparatus is a device selected from the group consisting of a scan-and-repeat mask aligner and a step-and-repeat mask aligner. 
     
     
       27. An apparatus for immersion lithography according to claim 20, further comprising a fluid-filter means for filtering the fluid. 
     
     
       28. An apparatus for emmersion lithography according to claim 20, further comprising:
 a fluid inlet for replenishing fluid in the moveable wafer stage; and   a fluid outlet for discharging fluid from the moveable wafer stage.   
     
     
       29. An apparatus for immersion lithography according to claim 20 further comprising mirror means for monitoring a position of the imaging lens and the wafer. 
     
     
       30. An apparatus for immersion lithography comprising:
 an imaging lens having a front surface;   a wafer having a top surface to be exposed, the wafer top surface positioned apart from the imaging lens front surface forming a gap;   a movable wafer stage means comprising a wafer holding means for holding the wafer in place, a fluid retaining means for retaining a fluid in the wafer stage means, a circulating means for circulating the fluid within the moveable wafer stage means, a temperature controlling means for controlling the temperature of the fluid within the wafer stage means, and a fluid filter means for filtering the fluid within the wafer stage means;   a fluid having a refractive index between about 1.0 and about 2.0 filling the gap; and   cover means for said fluid retaining means to protect the fluid around the imaging lens from particulates.   
     
     
       31. An apparatus for immersion lithography according to claim 30, wherein the gap is 5 mm or less. 
     
     
       32. A method for conducting immersion lithography comprising the steps of:
 providing an imaging lens having a front surface;   providing a moveable wafer stage means comprising a wafer holding means for holding the wafer in place, a fluid retaining means for retaining a fluid in the wafer stage means, a circulating means for circulating the fluid within the moveable wafer stage means, a temperature controlling means for controlling the temperature of the fluid within the wafer stage means, and a fluid filter means for filtering the fluid within the wafer stage means;   positioning a wafer on the wafer holding means, the wafer having a top surface to be exposed, the wafer top surface positioned apart from the imaging lens front surface forming a gap therebetween;   maintaining a fluid within the moveable wafer stage means having a refractive index between about 1.0 and about 2.0 in the gap, wherein the gap is less than 5 mm; and   moving the imaging lens in a longitudinal direction for focusing.   
     
     
       33. A method for conducting immersion lithography according to claim 32 further comprising the step of moving the wafer in a lateral direction for repeated exposures. 
     
     
       34. A method for conducting immersion lithography according to claim 32 further comprising the step of completely submerging the wafer in the fluid. 
     
     
       35. A method for conducting immersion lithography according to claim 32 further comprising the step of inducing the fluid to flow through the gap. 
     
     
       36. An apparatus for immersion lithography, comprising:
 a lens having a front surface;   a moveable wafer stage for supporting a wafer at a gap of less than 5 mm from the lens front surface, the moveable wafer stage formed to contain a fluid disposed within the gap, the moveable wafer stage having recirculation means for recirculating the fluid within the moveable wafer stage and having temperature control means for maintaining the temperature of the fluid within the movable wafer stage; and   the movable wafer stage further comprising cover means to protect the fluid around the imaging lens from particulates.   
     
     
       37. An apparatus for immersion lithography according to claim 36, the moveable wafer stage further comprising:
 fluid retaining means for maintaining the fluid in the gap between the front surface of the imaging lens and the top surface of the wafer when the wafer is not completely submerged in the fluid.   
     
     
       38. An apparatus for immersion lithography according to claim 36, the moveable wafer stage further comprising vacuum means for securely holding the supported wafer. 
     
     
       39. An apparatus for immersion lithography according to claim 36, wherein the moveable wafer stage is operable to move longitudinally for focusing. 
     
     
       40. An apparatus for immersion lithography according to claim 36, wherein the apparatus is a device selected from the group consisting of a scan-and-repeat mask aligner, a step-and-repeat mask aligner, and a proximity mask aligner. 
     
     
       41. An apparatus for immersion lithography, comprising:
 an imaging lens having a front surface;   a wafer having a top surface to be exposed, the wafer top surface positioned apart from the imaging lens front surface of the imaging lens thereby forming a gap of less than 5 mm;   a fluid filling the gap;   a fluid retaining means for maintaining the fluid in the gap between the front surface of the imaging lens and the top surface of the wafer when the wafer is not completely submerged in the fluid; and   cover means for said fluid retaining means to protect the fluid around the imaging lens from particulates.   
     
     
       42. An apparatus for immersion lithography, comprising:
 a lens having a front surface;   a stage for supporting a wafer at a gap of less than 5 mm from the lens front surface, the stage formed to contain a fluid disposed within the gap;   fluid retaining means for maintaining the fluid in the gap between the front surface of the imaging lens and the top surface of the wafer when the wafer is not completely submerged in the fluid; and   cover means for said fluid retaining means to protect the fluid around the imaging lens from particulates.   
     
     
       43. A method for conducting immersion lithography comprising the steps of:
 providing an imaging lens having a front surface;   positioning a wafer having a top surface to be exposed spaced-apart and juxtaposed to said front surface of the imaging lens;   maintaining a fluid having a refractive index between about 1.0 and about 2.0 in a gap formed in-between said front surface of the imaging lens and said top surface of the wafer; and   moving said imaging lens in a longitudinal direction for focusing.   
     
     
       44. A method for conducting immersion lithography according to claim 43 further comprising the step of moving said wafer in a lateral direction for repeated exposures. 
     
     
       45. A method for conducting immersion lithography according to claim 43 further comprising the step of controlling a temperature of said fluid. 
     
     
       46. A method for conducting immersion lithography according to claim 43 further comprising the step of submerging said wafer in the fluid. 
     
     
       47. A method for conducting immersion lithography according to claim 43 further comprising the step of controlling a flow of said fluid between said front surface of the imaging lens and said top surface of the wafer. 
     
     
       48. A method for conducting immersion lithography according to claim 43 further comprising the step of filtering said fluid to substantially remove all particles.