Hybrid electrostatic lens with increased natural frequency

Abstract

A composite electrostatic rod may include a body comprising a length L and cross sectional area A. The body may include an outer portion comprising a first material, and a core comprising a second material different than the first material and surrounded by the outer portion, wherein a natural frequency of the composite electrostatic rod is greater than that of a graphite rod having the length L and cross sectional area A.

What is claimed is: 
     
         1 . A composite electrostatic rod for use in an electrostatic lens, for controlling an ion beam for ion implantation, comprising:
 a body having a length L and cross sectional area A, the body comprising:   an outer portion comprising an upper shell and a lower shell fastened together, the upper and lower shells formed of a first material; and   a core formed from a second material different than the first material and surrounded by the outer portion, wherein a natural frequency of the composite electrostatic rod is greater than that of a graphite rod having the length L and cross sectional area A.   
     
     
         2 . The composite electrostatic rod of  claim 1 , comprising a strength-to-weight ratio greater than that of the graphite rod having the length L and the cross sectional area A. 
     
     
         3 . The composite electrostatic rod of  claim 1 , wherein the outer portion has an inner surface and the core has an outer surface, the inner surface and outer surface being in direct contact along the entire length of the body. 
     
     
         4 . The composite electrostatic rod of  claim 1 , further comprising a hollow region between the core and the outer portion. 
     
     
         5 . The composite electrostatic rod of  claim 1 , wherein the first material comprises graphite or silicon and the second material comprises aluminum, steel or carbon composite. 
     
     
         6 . The composite electrostatic rod of  claim 1 , further comprising a plurality of fasteners extending from the outer portion to the core and operable to fix the core to the outer portion. 
     
     
         7 . The composite electrostatic rod of  claim 1 , the outer portion comprising two sub-portions, the core and the two sub-portions operable to reversibly assembly into the composite electrostatic rod. 
     
     
         8 . The composite electrostatic rod of  claim 1 , the upper and lower shells defining, when assembled, one or more hollow regions within the electrostatic rod. 
     
     
         9 . The composite electrostatic rod of  claim 1 , the core comprising an “I”-shaped cross-section with a plurality of holes therethrough. 
     
     
         10 . The composite electrostatic rod of  claim 1 , the body having an elliptical shape in cross-section. 
     
     
         11 . A composite electrostatic rod for use in an electrostatic lens, for controlling an ion beam for ion implantation, the composite electrostatic rod comprising:
 a body having a length L and cross sectional area A, the body further comprising:
 an outer portion comprising a first material; and 
 a core comprising a second material different than the first material and surrounded by the outer portion; and 
   wherein a natural frequency of the composite electrostatic rod is greater than that of a graphite rod having the length L and cross sectional area A.   
     
     
         12 . The composite electrostatic rod of  claim 11 , the core comprising metal and the outer portion comprising a silicon coating. 
     
     
         13 . The composite electrostatic rod of  claim 11 , the outer portion comprising a graphite material, the core comprising aluminum. 
     
     
         14 . The composite electrostatic rod of  claim 11 , comprising a strength-to-weight ratio greater than that of the graphite rod having the length L and cross sectional area A. 
     
     
         15 . The composite electrostatic rod of  claim 11 , the outer portion comprising upper and lower shells that are joined to the core by a fastener. 
     
     
         16 . The composite electrostatic rod of  claim 11 , the outer portion comprising upper and lower shells that engage each other via at least one lap joint. 
     
     
         17 . The composite electrostatic rod of  claim 11 , the outer portion comprising upper and lower shells that encase the core and form at least one hollow region between the upper and lower shells and the core. 
     
     
         18 . The composite electrostatic rod of  claim 11 , the core comprising an “I”-shaped cross-section with a plurality of holes therethrough. 
     
     
         19 . The composite electrostatic rod of  claim 11 , the body having an elliptical shape in cross-section. 
     
     
         20 . A composite electrostatic rod for use in an electrostatic lens, for controlling an ion beam for ion implantation, comprising:
 a body having a length L and cross sectional area A, the body comprising:
 an outer portion comprising an upper shell and a lower shell engaged with each other, the upper and lower shells formed of a first material; and 
 a core having an “I” shaped cross-section, the core formed from a second material different than the first material, the core encased within the upper shell and the lower shell to form at least one hollow region between the upper and lower shells and the core; 
   wherein the upper and lower shells are coupled to the core via at least one fastener; and   wherein the composite electrostatic rod has a natural frequency and a strength-to-weight ratio which are greater than that of a graphite rod having the length L and cross sectional area A.