Charged-particle-beam projection-exposure method exhibiting aberration reduction through multiple deflector use
Patent 6027841 Issued on February 22, 2000. Estimated Expiration Date: December 10, 2018. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
Charged-particle-beam transfer-exposure apparatus are disclosed exhibiting reduced hybrid distortion. A charged particle beam passes through a mask and through a projection-lens assembly to form an image of a selected mask region on a wafer. Signals corresponding to the functions dx1 (Xw, Yw, Z, I, s), dy1 (Xw, Yw, Z, I, s), dx2 (Xw, Yw, Z, I, s), dy2 (Xw, Yw, Z, I, s), . . . , are generated by a computer and routed to respective deflectors to minimize deflection aberrations, wherein Xw, Yw are the coordinates of the deflected transfer region on the wafer, Z is the wafer height, I is the beam current passing through the pattern area in a mask region, and s is a variable pertaining to scattering of charged particles in the pattern. The signals routed to the various deflectors also take into account the function g(Xw, Yw, Z, I, s) which corrects deflection distortion.
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