US 4,929,838 A · Magnetic object lens for an electron beam exposure apparatus which processes a wafer carried on a continuously moving stage

Abstract

An electron beam exposure apparatus scans an electron beam in a limited space for electron beam lithography. A magnetic object lens of the apparatus has a lower pole piece facing an object to be processed, which is placed on a continuously moving stage to be exposed to the electron beam. A bore is opened in the lower pole piece which faces the object, and has a stripe-like cross-section to allow the passage of the electron beam. The shape of the opening inhibits the passage of undesirable leakage magnetic flux issued from the magnetic lens toward the object, and guides the electron beam to land on the object perpendicularly. With this configuration, deflection aberration of the deflection apparatus which is caused by an eddy current induced in the moving stage due to the magnetic flux reaching the stage is substantially prevented, and normal landing of the electron beam on the object is realized.

Claims23

Dependent claims

An electron beam exposure apparatus for projecting an electron beam onto an object which is continuously moving in a moving direction, by scanning the electron beam in a predetermined scanning space extending in a scanning direction, comprising:

a movable stage having a surface for supporting the object, said stage being substantially continuously movable in the moving direction;
a magnetic lens system including:
means for emitting electrons;
means for focusing the electrons into an electron beam, said focusing means having a magnetic object lens comprising:
a coil for generating magnetic flux;
an upper pole piece made of magnetic material and positioned adjacent said coil;
and
a lower pole piece made of magnetic material, positioned adjacent said coil and disposed to face the object, said lower pole piece having an opening coincident with the predetermined scanning space of the electron beam, the electron beam passing through said opening, said lower pole piece substantially preventing magnetic flux generated by said lens from reaching said stage;
and
means for deflecting the electron beam.

7 more elements

Dependencies are inferred from the claim text.

Magnetic object lens for an electron beam exposure apparatus which processes a wafer carried on a continuously moving stage

Life of this patent

Magnetic object lens for an electron beam exposure apparatus which processes a wafer carried on a continuously moving stage

Life of this patent

Abstract

Claims23