Aperture in a semiconductor material, and the production and use thereof

• Main Authors: Kassing, Rainer, Mihalcea, Christophe, Oesterschulze, Egbert
• Format: Patent
• Language: English
• Published: 21.09.2004

The invention relates to a method for producing an aperture in a semiconductor material, for example (100)-oriented or polycrystalline silicon. Such apertures, whose size is in the micrometer range or below, are used, for example, as a component of probes for scanning near-field optical microscopes (SNOM). With this method, optical surface properties can be inspected with sub-wavelength resolution. As with any other scanning optical microscope, the resolution achievable by the scanning near-field optical microscope is limited by the geometry and the dimensions of the probe, which means in particular, the aperture and its distance from the surface of the sample piece. In order to achieve sub-wavelength resolution the light-emitting or detecting area of the probe must have lateral dimensions below 100 nm. In the prior art, there is no lack of attempts at producing such small dimensioned reproducible apertures in the 100 nm range or below. A method known from the prior art is shown schematically in FIG. . reflects the cross-section through a semiconductor wafer having an upper surface and a lower surface . The upper surface comprises a plurality of cavities , for example in the form of an inverse pyramid , preferably produced by means of anisotropic etching. Thereafter, the lower surface of the semiconductor wafer , which consists of (100)-oriented silicon, for example, is etched back, particularly by means of anisotropic etching until the tips of the inverse pyramids are exposed, thus producing an aperture , as shown schematically by the first and second illustrations in . The opening of the first aperture is too wide, the opening of the second aperture is ideal, while in the third example, the tip of the inverse pyramid has not yet opened at all. The invention relates to a method for producing an aperture () in a semiconductor material () comprising the following steps: Preparing a semiconductor wafer (), for example, a (100)-oriented silicon wafer having an upper surface () and a lower surface (); producing a cavity () with a side wall () in the upper surface () of the semiconductor wafer () by partially etching said upper surface (), whereby the cavity () comprises a closed bottom area () which faces the lower surface () and which preferably has, in particular, a convex or, in particular, a concave corner or edge or a curvature of this type. After depositing an oxide layer () on the semiconductor material () at least in the area of the cavity () by oxidizing the semiconductor material (), whereby the oxide layer () preferably comprises an inhomogeneity () in the bottom area (), the semiconductor material () is selectively etched back on the lower surface () of the semiconductor wafer () until at least the oxide layer (26) located in the bottom area () is exposed. Afterwards, the exposed oxide layer () is etched until it is at least severed. In addition, the invention relates to an aperture () in a semiconductor material () especially produced according to the inventive method, and to different uses of such an aperture ().