GB1477458A - Specimen stages for electron beam instruments - Google Patents

Abstract

1477458 Electron microscopes J S SHAH 28 Oct 1974 [30 July 1973] 36209/73 Heading H1D A specimen stage suitable for use in a scanning electron microscope, and which permits the maintenance of a humid atmosphere-up to atmospheric pressure-around the specimen, includes a specimen chamber having an outlet for connection to a pump, an aperture permitting entry of the electron beam into the chamber, and a moisture reservoir arranged to keep the interior of the reservoir moist. As shown, the specimen S is supported in a chamber 10 into which the scanning electron beam from the microscope column 19 enters via the aperture 34, the intermediate chamber 12, and the aperture 36. Chambers 12 and 10 are pumped via respective ducts 24 and 22, the latter of which is provided with a buffer vessel 25 to minimize pressure variations, the further duct 26 being connected to a water vapour or nitrogen/water vapour source (not shown), to keeep the cotton gauze pod 28 saturated. The apertures 34 and 36 may be of 0À5 mm diameter, and the chamber 10 may include a humidity monitor. The entire assembly is mounted on a plate 16 which is dismountably sealed at 20 to an aperture in the microscope column. In modified arrangements the upper wall 32 of chamber 12 may be of re-entrant conical shape (Fig. 2, not shown) to reduce the electron beam path through the intermediate chamber; further intermediate chambers may be provided above chamber 12 and below specimen chamber 10, (Fig. 3, not shown), to permit the use of a greater total pressure difference (Fig. 4, not shown), and, if desired, the reintroduction of the transmitted beam back into the microscope main column 19 for detection; the moistened pad 28 may be located at an external junction of the ducts 22 and 26, a single ductwhich may be provided with heating means to prevent condensation-extending from the pad to immediately above the specimens (Fig. 4, not shown). In the embodiment of Figure 5, the pad 28 and specimen S are housed in a common holder 70, and are separated by the perforated wall 72. The microscope output may be derived from the reflected electrons by means of a scintillator or solid state detector, or from the specimen current.