US 6,632,722 B2 · Fiducial mark bodies for charged-particle-beam (CPB) microlithography, methods for making same, and CPB microlithography apparatus comprising same

Abstract

Fiducial mark bodies are provided for use in CPB microlithography apparatus and methods. Such bodies are especially useful for attachment to the wafer stage of such apparatus, for measuring a distance between a reference position of the CPB-optical system of the apparatus and a reference position of an optical-based alignment sensor of the apparatus. The mark bodies provide improved accuracy of these and other positional measurements. A typical mark body is made of a substrate plate (e.g., quartz or quartz-ceramic) having a low coefficient of thermal expansion. Mark elements are defined on the substrate plate by a layer of heavy metal (e.g. are Ta, W, or Pt). The mark body includes a surficial or interior layer of an electrically conductive light metal that prevents electrostatic charging of the mark body and can be connected to ground.

Claims9

Dependent claims

A method for fabricating a fiducial mark body for placement on a wafer stage of charged-particle-beam (CPB) microlithography apparatus and used to perform alignments of said apparatus, the method comprising:

providing an electrically non-conductive substrate plate made of a material having a coefficient of thermal expansion of 10−7/° C. or less;
applying a layer of a heavy metal to the substrate plate, the layer having a thickness greater than a critical thickness of the heavy metal;
defining, in the layer of heavy metal, mark elements;
removing heavy metal from regions other than the mark elements such that the thickness of any remaining heavy metal other than the mark elements is in the range of zero to a thickness that is less than the critical thickness of the heavy metal;
and
applying a layer of an electrically conductive material to the substrate plate, the layer having a thickness less than a critical thickness of the electrically conductive material.

3 more elements

Dependencies are inferred from the claim text.

Fiducial mark bodies for charged-particle-beam (CPB) microlithography, methods for making same, and CPB microlithography apparatus comprising same

Life of this patent

Fiducial mark bodies for charged-particle-beam (CPB) microlithography, methods for making same, and CPB microlithography apparatus comprising same

Life of this patent

Abstract

Claims9