Electron sources utilizing patterned negative electron affinity photocathodes

An electron source comprising:

• a light-transmissive substrate;
• a negative electron affinity active layer disposed on said substrate, said active layer having a conduction band;
• a patterned mask associated with said active layer, said mask having one or more openings that define areas of said active layer for emission of electrons;
• a light beam generator for directing a light beam through said light-transmissive substrate at said active layer for exciting electrons into the conduction band of said active layer;
• electron optics for forming the electrons emitted from the emission areas of said active layer into an electron beam;
• and
• a vacuum enclosure for maintaining said active layer at high vacuum such that electrons in the conduction band of said active layer have higher energies than electrons in the vacuum enclosure adjacent to said active layer and have a high probability of emission into the vacuum enclosure from the emission areas of said active layer.

An electron beam system comprising:

• an electron source comprising:
• a light-transmissive substrate;
• a negative electron affinity active layer disposed on said substrate, said active layer having a conduction band;
• a patterned mask associated with said active layer, said mask having one or more openings that define areas of said active layer for emission of electrons;
• a light beam generator for directing a light beam through said light-transmissive substrate at said active layer for exciting electrons into the conduction band of said active layer;
• source electron optics for forming the electrons emitted from the emission areas of said active layer into an electron beam;
• and
• a source vacuum enclosure for maintaining said active layer at high vacuum such that electrons in the conduction band of said active layer have higher energies than electrons in the source vacuum enclosure adjacent to said active layer and have a high probability of emission into the source vacuum enclosure from the emission areas of said active layer;
• a main vacuum enclosure for receiving said electron beam from said electron source and for holding a workpiece for processing by said electron beam;
• and
• main electron optics located within said main vacuum enclosure for directing said electron beam to said workpiece.

A negative electron affinity photocathode comprising:

• a light-transmissive substrate;
• an inactive layer disposed on said substrate;
• and
• one or more pillars of negative electron affinity active material extending through said inactive layer from said substrate to a surface of said inactive layer, said pillars defining areas for emission of electrons by negative electron affinity when said pillars are stimulated by a light beam directed through said substrate.