Abstract: An electron image projector for projecting mask patterns with unity magnification onto a semiconductor slice comprises a cathode from which emitted electrons are accelerated by a uniform electric field and focussed by a uniform magnetic field onto a target. To reduce the dependency of electron trajectories on the local shape and disposition of the target, the uniform electric field is applied by an accelerating voltage between the cathode and a grid electrode acting as the anode between the cathode and target. The grid is positioned at a first magnetic focus, and the target is positioned at a second magnetic focus of the uniform magnetic field. A small voltage much less than the accelerating voltage may be applied between the grid and the target to obtain correct focussing. Structure is also provided to move the grid parallel to the target during exposure in order to prevent the grid pattern from being reproduced on the target.

Abstract: A step-and-repeat electron image projector for transferring mask patterns repeatedly from a photoemissive cathode reticle (1) onto a target (3) with high resolution capabilities. Accelerated by a uniform electric field E and focussed by a uniform magnetic field H, a patterned electron beam is projected from the reticle (1) onto an area of the target with unity magnification. The electric field E is established between the cathode reticle and an electron permeable anode grid (2) situated between the cathode reticle and the target. Alignment of the beam and the target is effected by detecting electrons backscattered from reference markers (30) on the target with a backscattered electron detector (D) being located between the grid and the target. After exposing one area, the target is moved stepwise on an X-Y table (100) to expose an adjacent area, this procedure being repeated until the entire target has been exposed.

Abstract: An electron image projector for transferring mask patterns onto a semiconductor wafer comprises a patterned photoemissive cathode mask (4) and a target (3) formed by the semiconductor wafer (11) coated with an electron sensitive resist (10). Accelerated by a uniform electric field E and focussed by a uniform magnetic field H a patterned electron beam is projected from the cathode onto the target with unity magnification. The electric field E is established between the cathode and an electron permeable anode grid (2) situated between the cathode and the target. The anode grid comprises a plurality of mutually parallel slats (21,31) spaced apart by elongate electron permeable regions (22,32). The grid may be formed for example by an apertured silicon wafer (see FIG. 2) or conductive sheet, or by metal wires stretched across a metal annulus (see FIG. 3).

Abstract: An electrostatic chuck (1) for holding a semiconductor wafer (5) comprises a dielectric layer (4) on a supporting electrode (2). The wafer is clamped flat against the dielectric layer when a potential difference is applied between the wafer and the electrode. The dielectric is loaded with a thermally conductive material to improve the dissipation of heat generated in the wafer during a processing treatment such as exposure to an electron beam. The dielectric also has charge retention properties so that the wafer can be transported still clamped to the chuck without the need for a permanent electrical connection nor additional mechanical clamping members.

Abstract: A layer of electron-sensitive resist on a semiconductor substrate is exposed to a patterned electron beam emitted from an erasable photocathode mask in an electron image projector. The mask is formed from a transparent plate, such as quartz, on which a layer of cesium iodide or other photoemissive material is provided. A photoemissive pattern is defined in this layer by selective direct exposure to a beam of photons, electrons, or ions, preferably in an evacuated environment containing carbon whereby the photoemission of the exposed areas of the layer is lowered. Alternatively, using a beam of charged particles with a relatively high current density, the exposed parts of the layer are actually removed by evaporation. In either case, the patterned layer can be removed by rinsing in water and the transparent plate can be reused with the same or different photoemissive pattern.

Abstract: An electron image projector for transferring mask patterns onto a semiconductor wafer comprises a patterned photoemissive cathode mask and a target formed by the semiconductor wafer coated with an electron sensitive resist. A patterned electron beam is projected from the cathode onto the target with unity magnification by acceleration with a uniform electric field E and focussing by a uniform magnetic field H. The electric field E is established between the cathode and an electron permeable anode grid situated between the cathode and the target. For fast alignment with low power consumption, beam deflection is achieved electrostatically. The electrostatic deflection plates which may be integral with the anode grid or form part of a further grid, are arranged for deflecting at least part of the beam as it travels from the anode grid to the target. In one arrangement to correct for misalignment, the entire beam is deflected in the same direction.

Abstract: A layer of electron sensitive resist on a semiconductor substrate is exposed to a patterned electron beam emitted from an erasable photocathode mask in an electron image projector. The mask is formed from a transparent plate, such as quartz, on which a layer of caesium iodide or other photoemissive material is provided. A photoemissive pattern is defined in this layer by selective direct exposure to a beam of photons, electrons, or ions, preferably in an evacuated environment containing carbon whereby the photoemission of the exposed areas of the layer is lowered. Alternatively, using a beam of charged particles with a relatively high current density, the exposed parts of the layer are actually removed by evaporation. In either case, the patterned layer can be removed by rinsing in water and the transparent plate can be reused with the same or different photoemissive pattern.

Abstract: An electrostatic chuck for holding a simiconductor wafer flat in a charged particle beam machine has thermally conductive portions for supporting the wafer. An electrically conductive member, for example a grid, has parts which extend between the thermally-conductive portions and is separated from the wafer by a dielectric layer. The wafer is clamped against the chuck by the electrostatic force set up across the dielectric layer when a potential difference is applied between the conductive wafer and the conductive member. Heat generated in the wafer by the bombardment of charged particles can be dissipated readily via the thermally conductive portions. The wafer can be electrically contacted at its back surface if the portions are also electrically conductive. To enhance thermal conduction away from the wafer, the conductive portions can protrude from the dielectric layer.