Charged-particle-beam optical systems and microlithography apparatus comprising a non-absorbing shaping aperture

In a method for microlithographically exposing a pattern, defined by a reticle, onto a sensitive substrate using a charged particle beam propagating from a source through an illumination-optical system to the reticle, and from the reticle through a projection-optical system to a sensitive substrate, a method for shaping the charged particle beam, comprising:

• situating a shaping aperture so as to receive the charged particle beam, the shaping aperture comprising a thin-film membrane defining an aperture opening that transmits at least a portion of the charged particle beam incident on the shaping aperture, and the thin-film membrane being configured to scatter the charged particles of the beam incident on the membrane without absorbing the incident charged particles, thereby allowing the scattered charged particles to propagate downstream of the shaping aperture;
• passing the charged particle beam through the aperture opening of the shaping aperture to form a shaped beam propagating downstream of the shaping aperture;
• situating a screening aperture downstream of the shaping aperture at a location at which the shaped beam forms a crossover, the screening aperture comprising a conductive sheet defining an aperture opening having a width dimension corresponding to a width dimension of the crossover so as to allow the shaped beam to pass through the aperture opening, the conductive sheet being sufficiently thick in an optical-axis direction so as to absorb charged particles incident on the sheet;
• and
• passing the charged particle beam through the aperture opening of the screening aperture while absorbing charged particles, including charged particles scattered during transmission through the thin-film membrane of the shaping aperture, incident on the conductive sheet of the screening aperture.

A CPB microlithography method, comprising:

• in an illumination-optical system directing a charged-particle illumination beam to a shaping aperture comprising a thin-film membrane defining an aperture opening that transmits at least a portion of the illumination beam incident on the shaping aperture, the thin-film membrane being configured to scatter charged particles of the illumination beam incident on the membrane without absorbing the incident charged particles;
• passing the illumination beam through the aperture opening of the shaping aperture to form a shaped beam propagating downstream of the shaping aperture along with charged particles scattered by passage through the thin-film membrane of the shaping aperture;
• causing the shaped beam to form a crossover downstream of the shaping aperture;
• at the crossover causing the shaped beam to be incident on a screening aperture comprising a conductive sheet defining an aperture opening and being sufficiently thick so as to absorb charged particles incident on the sheet;
• passing the shaped illumination beam through the aperture opening of the screening aperture while absorbing scattered charged particles incident on the sheet, thereby blocking propagation of the scattered charged particles downstream of the screening aperture;
• directing the shaped illumination beam to a selected region on a pattern-defining reticle;
• and
• passing the charged particle beam, that has passed through the reticle, through a projection-optical system to a sensitive substrate.

A device-manufacturing method, comprising:

• defining a pattern on a reticle;
• and
• using a charged particle beam, transferring the pattern from the reticle to a sensitive substrate using a microlithography method comprising the steps of
• (1) in an illumination-optical system directing a charged-particle illumination beam to a shaping aperture comprising a thin-film membrane defining an aperture opening that transmits at least a portion of the illumination beam incident on the shaping aperture, the thin-film membrane being configured to scatter charged particles of the illumination beam incident on the membrane without absorbing the incident charged particles;
• (2) passing the illumination beam through the aperture opening of the shaping aperture to form a shaped beam propagating downstream of the shaping aperture along with charged particles scattered by passage through the thin-film membrane of the shaping aperture;
• (3) causing the shaped beam to form a crossover downstream of the shaping aperture;
• (4) at the crossover causing the shaped beam to be incident on a screening aperture comprising a conductive sheet defining an aperture opening and being sufficiently thick so as to absorb charged particles incident on sheet;
• (5) passing the shaped illumination beam through the aperture opening of the screening aperture while absorbing scattered charged particles incident on the sheet, thereby blocking propagation of the scattered charged particles downstream of the screening aperture;
• (6) directing the shaped illumination beam to a selected region on the reticle;
• and
• (7) passing the charged particle beam, that has passed through the reticle, through a projection-optical system to the sensitive substrate.